From 466b79a3ff5ffa3fcb7455379df83a9299e2d674 Mon Sep 17 00:00:00 2001
From: CAG2Mark <git@markng.com>
Date: Thu, 27 Aug 2026 15:34:34 +0800
Subject: [PATCH 01/13] Fix handler runtime bugs

---
 .../src/test/mlscript-compile/Runtime.mjs     | 35 ++++++++++++-------
 .../src/test/mlscript-compile/Runtime.mls     | 10 ++++--
 2 files changed, 30 insertions(+), 15 deletions(-)

diff --git a/hkmc2/shared/src/test/mlscript-compile/Runtime.mjs b/hkmc2/shared/src/test/mlscript-compile/Runtime.mjs
index a2a0088df9..d87c09cd60 100644
--- a/hkmc2/shared/src/test/mlscript-compile/Runtime.mjs
+++ b/hkmc2/shared/src/test/mlscript-compile/Runtime.mjs
@@ -1010,14 +1010,14 @@ lambda3 = (undefined, function (Runtime2, EffectHandle1, value) {
     }
   }
   static handleEffect(cur) {
-    let prevHandlerFrame, scrut, handlerFrame, saved, old, scrut1, scrut2, scrut3, tmp, tmp1, tmp2, tmp3;
+    let prevHandlerFrame, scrut, handlerFrame, saved, scrut1, scrut2, old, scrut3, scrut4, scrut5, scrut6, tmp, tmp1, tmp2, tmp3;
     prevHandlerFrame = cur.contTrace;
     lbl: while (true) {
-      let scrut4, scrut5;
-      scrut4 = prevHandlerFrame.nextHandler !== null;
-      if (scrut4 === true) {
-        scrut5 = prevHandlerFrame.nextHandler.handler !== cur.handler;
-        if (scrut5 === true) {
+      let scrut7, scrut8;
+      scrut7 = prevHandlerFrame.nextHandler !== null;
+      if (scrut7 === true) {
+        scrut8 = prevHandlerFrame.nextHandler.handler !== cur.handler;
+        if (scrut8 === true) {
           prevHandlerFrame = prevHandlerFrame.nextHandler;
           continue lbl
         }
@@ -1030,6 +1030,14 @@ lambda3 = (undefined, function (Runtime2, EffectHandle1, value) {
     }
     handlerFrame = prevHandlerFrame.nextHandler;
     saved = new Runtime.ContTrace.class(handlerFrame.next, cur.contTrace.last, handlerFrame.nextHandler, cur.contTrace.lastHandler, false);
+    scrut1 = cur.contTrace.last === handlerFrame;
+    if (scrut1 === true) {
+      saved.last = saved;
+    }
+    scrut2 = cur.contTrace.lastHandler === handlerFrame;
+    if (scrut2 === true) {
+      saved.lastHandler = saved;
+    }
     cur.contTrace.last = handlerFrame;
     cur.contTrace.lastHandler = handlerFrame;
     handlerFrame.next = null;
@@ -1045,16 +1053,19 @@ lambda3 = (undefined, function (Runtime2, EffectHandle1, value) {
     } finally {
       Runtime.stackDepth = old;
     }
-    scrut1 = Runtime.curEffect !== null;
-    if (scrut1 === true) {
+    scrut3 = Runtime.curEffect !== null;
+    if (scrut3 === true) {
       cur = Runtime.curEffect;
-      scrut2 = saved.next !== null;
-      if (scrut2 === true) {
+      scrut4 = saved.next !== null;
+      if (scrut4 === true) {
         cur.contTrace.last.next = saved.next;
+      }
+      scrut5 = saved.last !== saved;
+      if (scrut5 === true) {
         cur.contTrace.last = saved.last;
       }
-      scrut3 = saved.nextHandler !== null;
-      if (scrut3 === true) {
+      scrut6 = saved.nextHandler !== null;
+      if (scrut6 === true) {
         cur.contTrace.lastHandler.nextHandler = saved.nextHandler;
         cur.contTrace.lastHandler = saved.lastHandler;
         return cur
diff --git a/hkmc2/shared/src/test/mlscript-compile/Runtime.mls b/hkmc2/shared/src/test/mlscript-compile/Runtime.mls
index e9f0dfdbd8..290d3d99d6 100644
--- a/hkmc2/shared/src/test/mlscript-compile/Runtime.mls
+++ b/hkmc2/shared/src/test/mlscript-compile/Runtime.mls
@@ -412,6 +412,10 @@ fun handleEffect(cur) =
     cur.contTrace.lastHandler,
     false
   )
+  
+  if cur.contTrace.last === handlerFrame do set saved.last = saved
+  if cur.contTrace.lastHandler === handlerFrame do set saved.lastHandler = saved
+  
   set
     cur.contTrace.last = handlerFrame
     cur.contTrace.lastHandler = handlerFrame
@@ -425,9 +429,9 @@ fun handleEffect(cur) =
     set cur = curEffect
     // relink the saved frames
     if saved.next !== null do
-      set
-        cur.contTrace.last.next = saved.next
-        cur.contTrace.last = saved.last
+      set cur.contTrace.last.next = saved.next
+    if saved.last !== saved do
+      set cur.contTrace.last = saved.last
     if saved.nextHandler !== null do
       set
         cur.contTrace.lastHandler.nextHandler = saved.nextHandler

From 6d310cb0914a8c3ce75ebd6f00af2cea302ead77 Mon Sep 17 00:00:00 2001
From: CAG2Mark <git@markng.com>
Date: Thu, 27 Aug 2026 15:34:56 +0800
Subject: [PATCH 02/13] WIP: Tailrec fixes

---
 .../main/scala/hkmc2/codegen/TailRecOpt.scala | 86 ++++++++++++-------
 hkmc2/shared/src/test/mlscript/HkScratch.mls  | 13 +++
 .../test/mlscript/tailrec/MultiArgLists.mls   |  2 +-
 .../src/test/mlscript/tailrec/TailRecOpt.mls  | 60 +++++++++++--
 4 files changed, 123 insertions(+), 38 deletions(-)

diff --git a/hkmc2/shared/src/main/scala/hkmc2/codegen/TailRecOpt.scala b/hkmc2/shared/src/main/scala/hkmc2/codegen/TailRecOpt.scala
index 23c8ff7ed8..181139009f 100644
--- a/hkmc2/shared/src/main/scala/hkmc2/codegen/TailRecOpt.scala
+++ b/hkmc2/shared/src/main/scala/hkmc2/codegen/TailRecOpt.scala
@@ -249,7 +249,55 @@ class TailRecOpt(checkAnnotations: Bool)(using State, TL, Raise):
       CallArgsResult.Success(hd.appended(rest))
     else
       CallArgsResult.Success(hd)
-    
+  
+  /**
+    * Applies a parameter list to an argument list, both of which could contain arbitrary spreads.
+    *
+    * @param plist The parameter list to apply.
+    * @param args The argument list.
+    * @return A tuple `(Block => Block, List[Path])`, where:
+    * - The first parameter contains the code that breaks up the arguments into the shape expected by the parameter list, and
+    *   should be applied to the remaining code;
+    * - The second parameter is a list of paths containing the arguments in order. If there is a spread parameter, it will be
+    *   the last one.
+    */
+  def forceSpread(plist: ParamList, args: List[Arg]): (Block => Block, List[Path]) =
+    // Forcibly spread the args in an array.
+    // Assume the lengths are correct
+    val paramList = plist.params
+    val restParam = plist.restParam
+    
+    val tupleSym = TempSymbol(N, "argList")
+  
+    val tupleRes = Tuple(false, args)
+    
+    // Main args
+    def mainArgs(rest: List[Path]) = (0 until paramList.size).toList.foldRight(rest):
+      case (n, acc) => DynSelect(tupleSym.asSimpleRef, Value.Lit(Tree.IntLit(n)), true) :: acc
+    
+    // If the rest param exists, append a slice
+    val (initialBlk: (Block => Block), pathList: List[Path]) =
+      if restParam.isDefined then
+        val sliceResSym = TempSymbol(N, "sliceRes")
+        // runtime.Tuple.slice(tupleSym, paramList.length, 0)
+        val sliceRes = Call(
+          State.runtimeSymbol.asSimpleRef
+            .sel(Tree.Ident("Tuple"), State.tupleSymbol)
+            .sel(Tree.Ident("slice"), State.tupleSliceSymbol),
+          (tupleSym.asSimpleRef.asArg
+            :: Value.Lit(Tree.IntLit(paramList.length)).asArg
+            :: Value.Lit(Tree.IntLit(0)).asArg
+            :: Nil) ne_:: Nil
+        )(CallMetadata.defaultMlsFun)
+        val blk = blockBuilder
+          .assignScoped(tupleSym, tupleRes)
+          .assignScoped(sliceResSym, sliceRes)
+        (blk, mainArgs(sliceResSym.asSimpleRef :: Nil))
+      else
+        (blockBuilder.assignScoped(tupleSym, tupleRes), mainArgs(Nil))
+    end val
+    (initialBlk, pathList)
+  
   def optScc(scc: SccOfCalls, owner: Opt[InnerSymbol])(using accessInfo: (ScopeData, AccessMap)): (Opt[FunDefn], List[FunDefn]) =
     // sort the functions so the order is more predictable
     val funs = scc.funs.sortBy(f => f.dSym.uid)
@@ -366,6 +414,10 @@ class TailRecOpt(checkAnnotations: Bool)(using State, TL, Raise):
       
       override def applyBlock(b: Block): Block = b match
         // Note: the args in `c` have already been rewritten to point to the symbols in `paramSyms`.
+        // We explicitly rewrite *all* fully applied calls to functions within the SCC. Tail calls are rewritten using a
+        // `continue`, while other calls are rewritten as a call to the merged function. This is to make the tailrec
+        // optimizer pass idempotent. Without this, the subsequent tailrec optimizer passes could see the merged and wrapper
+        // functions as an SCC and try to rewrite the wrapper's tail call.
         case TailCallShape(calleeSym, c) => dSymIds.get(calleeSym) match
           case None => super.applyBlock(b)
           case Some(id) =>
@@ -447,43 +499,13 @@ class TailRecOpt(checkAnnotations: Bool)(using State, TL, Raise):
                   case CallArgsResult.ForceSpread =>
                     // Forcibly spread the args in an array.
                     // Assume the lengths are correct
-                    val paramList = ogParamList.params
-                    val restParam = ogParamList.restParam
-                    
-                    val tupleSym = TempSymbol(N, "argList")
                     
                     // We can safely remove all of the symbols from this parameter list from `assignedSyms` at this stage,
                     // because the RHS of every parameter will be computed when spreading them in the tuple, which happens
                     // before any of the param symbols are assigned to.
                     assignedSyms --= thisParamSyms
                     paramRewriter.applyArgs(ogArgs): newArgs =>
-                      val tupleRes = Tuple(false, newArgs)
-                      
-                      // Main args
-                      def mainArgs(rest: List[Path]) = (0 until paramList.size).toList.foldRight(rest):
-                        case (n, acc) => DynSelect(tupleSym.asSimpleRef, Value.Lit(Tree.IntLit(n)), true) :: acc
-                      
-                      // If the rest param exists, append a slice
-                      val (initialBlk: (Block => Block), pathList: List[Path]) =
-                        if restParam.isDefined then
-                          val sliceResSym = TempSymbol(N, "sliceRes")
-                          // runtime.Tuple.slice(tupleSym, paramList.length, 0)
-                          val sliceRes = Call(
-                            State.runtimeSymbol.asSimpleRef
-                              .sel(Tree.Ident("Tuple"), State.tupleSymbol)
-                              .sel(Tree.Ident("slice"), State.tupleSliceSymbol),
-                            (tupleSym.asSimpleRef.asArg
-                              :: Value.Lit(Tree.IntLit(paramList.length)).asArg
-                              :: Value.Lit(Tree.IntLit(0)).asArg
-                              :: Nil) ne_:: Nil
-                          )(CallMetadata.defaultMlsFun)
-                          val blk = blockBuilder
-                            .assignScoped(tupleSym, tupleRes)
-                            .assignScoped(sliceResSym, sliceRes)
-                          (blk, mainArgs(sliceResSym.asSimpleRef :: Nil))
-                        else
-                          (blockBuilder.assignScoped(tupleSym, tupleRes), mainArgs(Nil))
-                      end val
+                      val (initialBlk, pathList) = forceSpread(ogParamList, newArgs)
                       val paramAssignments = (thisParamSyms zip pathList).foldRight[Block](rest):
                         case ((sym, path), restBlk) => Assign(sym, path, restBlk)
                     
diff --git a/hkmc2/shared/src/test/mlscript/HkScratch.mls b/hkmc2/shared/src/test/mlscript/HkScratch.mls
index 48d7326643..a2851f5993 100644
--- a/hkmc2/shared/src/test/mlscript/HkScratch.mls
+++ b/hkmc2/shared/src/test/mlscript/HkScratch.mls
@@ -8,4 +8,17 @@
 // :d
 // :todo
 
+open annotations
 
+:sjs
+@inline fun f(x, y, ...z) = [x, y, z]
+//│ ————————————| JS (unsanitized) |————————————————————————————————————————————————————————————————————
+//│ let f; f = function f(x, y, ...z) { return globalThis.Object.freeze([ x, y, z ]) };
+//│ —————————————————| Output |—————————————————————————————————————————————————————————————————————————
+
+:sjs
+f(1, 2, 3, 4)
+//│ ————————————| JS (unsanitized) |————————————————————————————————————————————————————————————————————
+//│ let z; z = [ 3, 4 ]; return globalThis.Object.freeze([ 1, 2, z ])
+//│ —————————————————| Output |—————————————————————————————————————————————————————————————————————————
+//│ = [1, 2, [3, 4]]
diff --git a/hkmc2/shared/src/test/mlscript/tailrec/MultiArgLists.mls b/hkmc2/shared/src/test/mlscript/tailrec/MultiArgLists.mls
index 2a743d9cbc..bce6dc5719 100644
--- a/hkmc2/shared/src/test/mlscript/tailrec/MultiArgLists.mls
+++ b/hkmc2/shared/src/test/mlscript/tailrec/MultiArgLists.mls
@@ -227,7 +227,7 @@ fun g(n)(m) =
 //│             return [param5, param6]
 //│         end
 //│       1 =>
-//│         let tmp, tmp1, tmp2, tmp3, param1_tmp, argList, param0_tmp, inlinedVal, tmp4;
+//│         let tmp, tmp1, tmp2, tmp3, param1_tmp, param0_tmp, argList, inlinedVal, tmp4;
 //│         set tmp = -⁰(param0, 1);
 //│         set tmp1 = [1, 2];
 //│         set tmp2 = [3, 4];
diff --git a/hkmc2/shared/src/test/mlscript/tailrec/TailRecOpt.mls b/hkmc2/shared/src/test/mlscript/tailrec/TailRecOpt.mls
index fb446d28f6..7731c0a6b1 100644
--- a/hkmc2/shared/src/test/mlscript/tailrec/TailRecOpt.mls
+++ b/hkmc2/shared/src/test/mlscript/tailrec/TailRecOpt.mls
@@ -295,6 +295,56 @@ a.x
 //│ = 2
 //│ a = A(2)
 
+// Make sure the tailrec pass is idempotent
+:soir
+:noInline
+:todo
+:silent
+fun f(x) = g(x)
+fun g(x) =
+  f(x)
+  0
+//│ ——————————————| Optimized IR |——————————————————————————————————————————————————————————————————————
+//│ let f_g, f_f_g;
+//│ define f_f_g as fun f_f_g⁰(id, param0, param1) {
+//│   loop loopLabel:
+//│     match id
+//│       0 =>
+//│         let param0_tmp;
+//│         set param0_tmp = param0;
+//│         set param0 = 0;
+//│         set param1 = param0_tmp;
+//│         set id = 1;
+//│         continue loopLabel
+//│       1 =>
+//│         loop loopLabel1:
+//│           match param0
+//│             0 =>
+//│               set param0 = 1;
+//│               continue loopLabel1
+//│             1 =>
+//│               do f⁶(param1);
+//│               return 0
+//│             else
+//│               end
+//│           end
+//│         end
+//│       else
+//│         end
+//│     end
+//│   end
+//│ };
+//│ define f_g as fun f_g¹(id, param0) {
+//│   return f_f_g⁰(1, id, param0)
+//│ };
+//│ define f⁷ as fun f⁶(x) {
+//│   return f_f_g⁰(0, x, undefined)
+//│ };
+//│ define g⁴ as fun g⁵(x) { return f_g¹(1, x) };
+//│ end
+//│ —————————————————| Output |—————————————————————————————————————————————————————————————————————————
+//│ FAILURE: Unexpected lack of error to fix
+
 // Functions inside module definitions are lifted to the top level. This means they cannot yet be optimized.
 :lift
 :fixme
@@ -304,10 +354,10 @@ module A with
     @tailcall g(x - 1)
 A.f(10000)
 //│ ╔══[COMPILATION ERROR] This tail call exits the current scope and is not optimized.
-//│ ║  l.303: 	    fun g(x) = if x < 0 then 0 else @tailcall f(x)
+//│ ║  l.353: 	    fun g(x) = if x < 0 then 0 else @tailcall f(x)
 //│ ╙──       	                                              ^^^^
 //│ ╔══[COMPILATION ERROR] This tail call exits the current scope and is not optimized.
-//│ ║  l.304: 	    @tailcall g(x - 1)
+//│ ║  l.354: 	    @tailcall g(x - 1)
 //│ ╙──       	              ^^^^^^^^
 //│ = 0
 
@@ -334,12 +384,12 @@ class A with
   fun g(x) = if x == 0 then 1 else @tailcall f(x - 1)
 (new A).f(10)
 //│ ╔══[COMPILATION ERROR] Calls from class methods cannot yet be marked @tailcall.
-//│ ║  l.333: 	  @tailrec fun f(x) = if x == 0 then 0 else @tailcall g(x - 1)
+//│ ║  l.383: 	  @tailrec fun f(x) = if x == 0 then 0 else @tailcall g(x - 1)
 //│ ╙──       	                                                      ^^^^^^^^
 //│ ╔══[COMPILATION ERROR] Class methods may not yet be marked @tailrec.
-//│ ║  l.333: 	  @tailrec fun f(x) = if x == 0 then 0 else @tailcall g(x - 1)
+//│ ║  l.383: 	  @tailrec fun f(x) = if x == 0 then 0 else @tailcall g(x - 1)
 //│ ╙──       	               ^
 //│ ╔══[COMPILATION ERROR] Calls from class methods cannot yet be marked @tailcall.
-//│ ║  l.334: 	  fun g(x) = if x == 0 then 1 else @tailcall f(x - 1)
+//│ ║  l.384: 	  fun g(x) = if x == 0 then 1 else @tailcall f(x - 1)
 //│ ╙──       	                                             ^^^^^^^^
 //│ = 0

From 786ccdb0dec345dc1254a0caa90d59837ce2cf75 Mon Sep 17 00:00:00 2001
From: CAG2Mark <git@markng.com>
Date: Thu, 27 Aug 2026 16:35:10 +0800
Subject: [PATCH 03/13] Tailrec fixes

---
 .../src/main/scala/hkmc2/codegen/Block.scala  |   1 +
 .../main/scala/hkmc2/codegen/TailRecOpt.scala |  87 +++++++++-----
 hkmc2/shared/src/test/mlscript/HkScratch.mls  |  12 --
 .../test/mlscript/tailrec/MultiArgLists.mls   | 112 ++++++++++++++++++
 .../src/test/mlscript/tailrec/TailRecOpt.mls  |  44 ++-----
 5 files changed, 184 insertions(+), 72 deletions(-)

diff --git a/hkmc2/shared/src/main/scala/hkmc2/codegen/Block.scala b/hkmc2/shared/src/main/scala/hkmc2/codegen/Block.scala
index 7106f6577d..bcc34c550e 100644
--- a/hkmc2/shared/src/main/scala/hkmc2/codegen/Block.scala
+++ b/hkmc2/shared/src/main/scala/hkmc2/codegen/Block.scala
@@ -682,6 +682,7 @@ final case class FunDefn(
   lazy val affineInfo: Ls[Int] =
     annotations.collect:
       case Annot.Affine(whichParamList) => whichParamList
+  lazy val paramSyms: Ls[VarSymbol] = params.flatMap(_.paramSyms)
 
   // * This deliberately is not a lazy val: its initialization would synchronize on the JVM.
   // * Computing the summary is pure, and a reference write is atomic, so concurrent traversals may
diff --git a/hkmc2/shared/src/main/scala/hkmc2/codegen/TailRecOpt.scala b/hkmc2/shared/src/main/scala/hkmc2/codegen/TailRecOpt.scala
index 181139009f..eadebc7438 100644
--- a/hkmc2/shared/src/main/scala/hkmc2/codegen/TailRecOpt.scala
+++ b/hkmc2/shared/src/main/scala/hkmc2/codegen/TailRecOpt.scala
@@ -13,7 +13,6 @@ import hkmc2.syntax.{Tree, SpreadKind}
 import hkmc2.ScopeData.*
 import hkmc2.Lifter.AccessInfo
 import scala.collection.mutable.{ArrayBuffer, LinkedHashMap}
-import java.lang.instrument.ClassDefinition
 
 /*
 
@@ -207,11 +206,6 @@ class TailRecOpt(checkAnnotations: Bool)(using State, TL, Raise):
       val x = f(item)
       if x > l then x else l
   
-  def getParamSyms(f: FunDefn) = f.params.flatMap:
-    case ParamList(_, params, S(rest)) =>
-      params.map(_.sym).appended(rest.sym)
-    case p => p.params.map(_.sym)
-  
   def paramsLen(f: FunDefn): Int = f.params.foldLeft(0): (acc, head) =>
     acc + (if head.restParam.isDefined then 1 + head.params.length
       else head.params.length)
@@ -335,7 +329,7 @@ class TailRecOpt(checkAnnotations: Bool)(using State, TL, Raise):
     val maxParamLen = maxInt(funs, paramsLen)
     val paramSyms =
         if funs.length === 1 then
-          val syms = getParamSyms(funs.head)
+          val syms = funs.head.paramSyms
           if funs.head.params.length === 1 then syms
           else
             // Duplicate the params for the internal loop defn (see the doc at the
@@ -358,16 +352,24 @@ class TailRecOpt(checkAnnotations: Bool)(using State, TL, Raise):
     val dSymIds = funs.iterator.map(_.dSym).zipWithIndex.toMap
     val dSymToDefn = funs.iterator.map(f => f.dSym -> f).toMap
     val bms =
-      if funsLen === 1 then funs.head.sym
+      if funsLen === 1 then funs.head.params match
+        case _ :: Nil => funs.head.sym
+        case _ => BlockMemberSymbol(funs.head.sym.nme + "$tailrec", Nil, true)
       else BlockMemberSymbol(funs.iterator.map(_.sym.nme).mkString("_"), Nil, true)
     val dSym =
-      if funsLen === 1 then funs.head.dSym
+      if funsLen === 1 then funs.head.params match
+        case _ :: Nil => funs.head.dSym
+        case _ => TermSymbol(syntax.Fun, owner, Tree.Ident(bms.nme))
       else TermSymbol(syntax.Fun, owner, Tree.Ident(bms.nme))
     val loopSym = LabelSymbol(N, "loopLabel")
     val curIdSym = VarSymbol(Tree.Ident("id"))
     
+    val sel = owner match
+      case Some(value) => Select(value.asThis, Tree.Ident(bms.nme))(S(dSym))(false)
+      case None => bms.asMemberRef(dSym)
+    
     class FunRewriter(f: FunDefn) extends BlockTransformerShallow(SymbolSubst.Id):
-      val params = getParamSyms(f)
+      val params = f.paramSyms
       val paramsSet = f.params.toSet
       val paramsIdxes = params.zipWithIndex.toMap
       
@@ -414,10 +416,6 @@ class TailRecOpt(checkAnnotations: Bool)(using State, TL, Raise):
       
       override def applyBlock(b: Block): Block = b match
         // Note: the args in `c` have already been rewritten to point to the symbols in `paramSyms`.
-        // We explicitly rewrite *all* fully applied calls to functions within the SCC. Tail calls are rewritten using a
-        // `continue`, while other calls are rewritten as a call to the merged function. This is to make the tailrec
-        // optimizer pass idempotent. Without this, the subsequent tailrec optimizer passes could see the merged and wrapper
-        // functions as an SCC and try to rewrite the wrapper's tail call.
         case TailCallShape(calleeSym, c) => dSymIds.get(calleeSym) match
           case None => super.applyBlock(b)
           case Some(id) =>
@@ -520,6 +518,50 @@ class TailRecOpt(checkAnnotations: Bool)(using State, TL, Raise):
         // Not a tail call
         case _ => super.applyBlock(b)
       
+      // We explicitly rewrite *all* fully applied calls to functions within the SCC. Tail calls are rewritten using a
+      // `continue`, while other calls are rewritten as a call to the merged function. This is to make the tailrec
+      // optimizer pass idempotent. Without this, the subsequent tailrec optimizer passes could see the merged and wrapper
+      // functions as an SCC and try to rewrite the wrapper's tail call.
+      override def applyResult(r: Result)(k: Result => Block): Block = r match
+        case c @ Call(Value.MemberRef(bms, calleeSym: TermSymbol), args) => funsMap.get(calleeSym) match
+          case Some(callee) if isExactlySaturatedCall(c, callee) =>
+            val calleeParamsMap = paramSymsMap(callee.dSym)
+            val argListResults = callee.params.zip(c.argss).map:
+              case (params, args) => (params, params.paramSyms.map(calleeParamsMap), args, rewriteArgsList(callee, params, args))
+            // Note: even though the convention right now is to just have the first k_f arguments of the merged function be the arguments
+            // of each function f, where f has k_f total parameters, we still explicitly find the correct order of arguments without
+            // using this convention. This is because this assumption may not hold in the future, i.e. when arguments could be assigned
+            // types for the typed IR.
+            var pre = blockBuilder
+            val argsInOrder: List[Path] = argListResults.flatMap: (ogParams, thisParamSyms, args, argsRes) =>
+              argsRes match
+                case CallArgsResult.Success(res) => res.map:
+                  case r: Path => r
+                  case r: Result =>
+                    val newSym = TempSymbol(N)
+                    pre = pre.assignScoped(newSym, r)
+                    newSym.asPath
+                case CallArgsResult.ForceSpread =>
+                  val (initialBlk, paths) = forceSpread(ogParams, args)
+                  pre = pre.chain(initialBlk)
+                  paths
+            assert(callee.paramSyms.length === argsInOrder.length)
+            val argsMap = (callee.paramSyms.map(paramSymsMap(callee.dSym)) zip argsInOrder).toMap
+            val args = paramSyms.map: s =>
+              argsMap.get(s) match
+                case Some(pth) => Arg(N, pth)
+                case None => Arg(N, Value.Lit(Tree.UnitLit(false)))
+            val argsWithId = if funsLen > 1 then Value.Lit(Tree.IntLit(dSymIds(calleeSym))).asArg :: args else args
+            val call = Call(sel, argsWithId ne_:: Nil)(CallMetadata.defaultMlsFun)
+            pre.rest(k(call))
+            // f.paramSyms
+            // assert(assignmentsInOrder.length === )
+              
+            
+          case _ => super.applyResult(r)(k)
+        case _ => super.applyResult(r)(k)
+        
+      
       def rewrite(b: Block): Block =
         // Rewrite the result with symbols pointing to the merged function parameters and possibly the copied parameters (see `copiedParams`).
         val blk = applyBlock(symRewriter.applyBlock(b))
@@ -536,14 +578,10 @@ class TailRecOpt(checkAnnotations: Bool)(using State, TL, Raise):
     
     val loop = Label(loopSym, true, switch, End())
     
-    val sel = owner match
-      case Some(value) => Select(value.asThis, Tree.Ident(bms.nme))(S(dSym))(false)
-      case None => bms.asMemberRef(dSym)
-    
     val rewrittenFuns =
       if funsLen === 1 then Nil
       else funs.map: f =>
-        val paramArgs = getParamSyms(f).map(s => s.asSimpleRef.asArg)
+        val paramArgs = f.paramSyms.map(s => s.asSimpleRef.asArg)
         val args =
           Value.Lit(Tree.IntLit(dSymIds(f.dSym))).asArg
             :: paramArgs
@@ -566,21 +604,16 @@ class TailRecOpt(checkAnnotations: Bool)(using State, TL, Raise):
         // original multi-param-list interface and delegates to the flattened internal loop.
         val params = paramSyms.map(Param.simple(_))
         
-        val loopBms = BlockMemberSymbol(bms.nme + "$tailrec", Nil, true)
-        val loopDSym = TermSymbol(syntax.Fun, owner, Tree.Ident(loopBms.nme))
         val loopAnnots =
           if f.inline then Annot.Inline :: Annot.Private :: Nil
           else Annot.Private :: Nil
         val internalLoopDefn = FunDefn(
-          owner, loopBms, loopDSym,
+          owner, bms, dSym,
           PlainParamList(params) :: Nil,
           loop)(N, annotations = loopAnnots)
-        val paramArgs = getParamSyms(f).map(s => s.asSimpleRef.asArg)
-        val internalSel = owner match
-          case Some(value) => Select(value.asThis, Tree.Ident(loopBms.nme))(S(loopDSym))(false)
-          case None => loopBms.asMemberRef(loopDSym)
+        val paramArgs = f.paramSyms.map(s => s.asSimpleRef.asArg)
         val wrapperBod = Return(
-          Call(internalSel, paramArgs ne_:: Nil)(CallMetadata.defaultMlsFun),
+          Call(sel, paramArgs ne_:: Nil)(CallMetadata.defaultMlsFun),
         )
         val newAnnots = if f.inline then f.annotations else Annot.Inline :: f.annotations
         val wrapperDefn = FunDefn(f.owner, f.sym, f.dSym, f.params, wrapperBod)(
diff --git a/hkmc2/shared/src/test/mlscript/HkScratch.mls b/hkmc2/shared/src/test/mlscript/HkScratch.mls
index a2851f5993..ef38e8b363 100644
--- a/hkmc2/shared/src/test/mlscript/HkScratch.mls
+++ b/hkmc2/shared/src/test/mlscript/HkScratch.mls
@@ -8,17 +8,5 @@
 // :d
 // :todo
 
-open annotations
 
-:sjs
-@inline fun f(x, y, ...z) = [x, y, z]
-//│ ————————————| JS (unsanitized) |————————————————————————————————————————————————————————————————————
-//│ let f; f = function f(x, y, ...z) { return globalThis.Object.freeze([ x, y, z ]) };
-//│ —————————————————| Output |—————————————————————————————————————————————————————————————————————————
 
-:sjs
-f(1, 2, 3, 4)
-//│ ————————————| JS (unsanitized) |————————————————————————————————————————————————————————————————————
-//│ let z; z = [ 3, 4 ]; return globalThis.Object.freeze([ 1, 2, z ])
-//│ —————————————————| Output |—————————————————————————————————————————————————————————————————————————
-//│ = [1, 2, [3, 4]]
diff --git a/hkmc2/shared/src/test/mlscript/tailrec/MultiArgLists.mls b/hkmc2/shared/src/test/mlscript/tailrec/MultiArgLists.mls
index bce6dc5719..0634683980 100644
--- a/hkmc2/shared/src/test/mlscript/tailrec/MultiArgLists.mls
+++ b/hkmc2/shared/src/test/mlscript/tailrec/MultiArgLists.mls
@@ -399,3 +399,115 @@ fun f = loop(1000)(0)
 //│ };
 //│ end
 //│ —————————————————| Output |—————————————————————————————————————————————————————————————————————————
+
+// Ensure the function is inlined
+:soir
+fun loop(x)(y) =
+  if y === 0 then 0
+  else if x === 0 then 1 + loop(5)(y - 1)
+  else @tailcall loop(x - 1)(y)
+loop(5)(5)
+//│ ——————————————| Optimized IR |——————————————————————————————————————————————————————————————————————
+//│ let loop$tailrec;
+//│ @private
+//│ define loop$tailrec as fun loop$tailrec¹(x, y) {
+//│   loop loopLabel:
+//│     let scrut, scrut1, tmp, tmp1, tmp2;
+//│     set scrut = ===⁰(y, 0);
+//│     match scrut
+//│       true =>
+//│         return 0
+//│       else
+//│         set scrut1 = ===⁰(x, 0);
+//│         match scrut1
+//│           true =>
+//│             set tmp = -⁰(y, 1);
+//│             set tmp1 = loop$tailrec¹(5, tmp);
+//│             return +⁰(1, tmp1)
+//│           else
+//│             set tmp2 = -⁰(x, 1);
+//│             set x = tmp2;
+//│             continue loopLabel
+//│         end
+//│     end
+//│   unreachable /* Rest of abortive labelled block */
+//│ };
+//│ @inline
+//│ define loop⁴ as fun loop⁵(x)(y) { return loop$tailrec¹(x, y) };
+//│ return loop$tailrec¹(5, 5)
+//│ —————————————————| Output |—————————————————————————————————————————————————————————————————————————
+//│ = 5
+
+fun f(n)(a, b, c, d, ...e)(m) =
+  if n > 0 then @tailcall g(n)(m + 1)
+  else [e, m]
+fun g(n)(m) =
+  let res = f(n - 1)(...[1, 2], 3, ...[3, 4], ...[5, n], 7, n)(m)
+  print("hi!")
+  res
+
+:expect [[4, 5, 1, 7, 1], 9]
+g(10)(0)
+//│ > hi!
+//│ > hi!
+//│ > hi!
+//│ > hi!
+//│ > hi!
+//│ > hi!
+//│ > hi!
+//│ > hi!
+//│ > hi!
+//│ > hi!
+//│ = [[4, 5, 1, 7, 1], 9]
+
+:soir
+fun f(n)(a)(...z) =
+  if n > 0 then f(n - 1)(a)(...z) else if z is
+    [] then a
+    [x, ...xs] then
+      let res = f(n)(a + 1)(...xs)
+      print("hi!")
+      res
+//│ ——————————————| Optimized IR |——————————————————————————————————————————————————————————————————————
+//│ let f$tailrec;
+//│ @private
+//│ define f$tailrec as fun f$tailrec³(n, a, z) {
+//│   loop loopLabel:
+//│     let scrut, res, tmp, tmp1;
+//│     set scrut = >⁰(n, 0);
+//│     match scrut
+//│       true =>
+//│         set tmp = -⁰(n, 1);
+//│         set n = tmp;
+//│         continue loopLabel
+//│       else
+//│         match z
+//│           Array(0) =>
+//│             return a
+//│           Array(1+) =>
+//│             let inlinedVal, tmp2;
+//│             do runtime⁰.Tuple⁰.get⁰(z, 0);
+//│             set tmp2 = -¹(z.length﹖, 0);
+//│             set inlinedVal = z.slice﹖(1, tmp2);
+//│             set tmp1 = +⁰(a, 1);
+//│             set res = f$tailrec³(n, tmp1, inlinedVal);
+//│             do Predef⁰.print⁰("hi!");
+//│             return res
+//│           else
+//│             throw new globalThis⁰.Error⁰("match error")
+//│         end
+//│     end
+//│   unreachable /* Rest of abortive labelled block */
+//│ };
+//│ @inline
+//│ define f⁸ as fun f⁹(n)(a)(...z) { return f$tailrec³(n, a, z) };
+//│ end
+//│ —————————————————| Output |—————————————————————————————————————————————————————————————————————————
+
+:expect 4
+f(5)(0)(1, 2, 3, 4)
+//│ > hi!
+//│ > hi!
+//│ > hi!
+//│ > hi!
+//│ = 4
diff --git a/hkmc2/shared/src/test/mlscript/tailrec/TailRecOpt.mls b/hkmc2/shared/src/test/mlscript/tailrec/TailRecOpt.mls
index 7731c0a6b1..c9f59cc8e7 100644
--- a/hkmc2/shared/src/test/mlscript/tailrec/TailRecOpt.mls
+++ b/hkmc2/shared/src/test/mlscript/tailrec/TailRecOpt.mls
@@ -295,55 +295,33 @@ a.x
 //│ = 2
 //│ a = A(2)
 
-// Make sure the tailrec pass is idempotent
+// Make sure the tailrec pass is idempotent by ensuring non-tail calls to functions in the SCC are rewritten as calls to the loop definition.
 :soir
 :noInline
-:todo
-:silent
 fun f(x) = g(x)
 fun g(x) =
   f(x)
   0
 //│ ——————————————| Optimized IR |——————————————————————————————————————————————————————————————————————
-//│ let f_g, f_f_g;
-//│ define f_f_g as fun f_f_g⁰(id, param0, param1) {
+//│ let f_g;
+//│ define f_g as fun f_g¹(id, param0) {
 //│   loop loopLabel:
 //│     match id
 //│       0 =>
-//│         let param0_tmp;
-//│         set param0_tmp = param0;
-//│         set param0 = 0;
-//│         set param1 = param0_tmp;
 //│         set id = 1;
 //│         continue loopLabel
 //│       1 =>
-//│         loop loopLabel1:
-//│           match param0
-//│             0 =>
-//│               set param0 = 1;
-//│               continue loopLabel1
-//│             1 =>
-//│               do f⁶(param1);
-//│               return 0
-//│             else
-//│               end
-//│           end
-//│         end
+//│         do f_g¹(0, param0);
+//│         return 0
 //│       else
 //│         end
 //│     end
 //│   end
 //│ };
-//│ define f_g as fun f_g¹(id, param0) {
-//│   return f_f_g⁰(1, id, param0)
-//│ };
-//│ define f⁷ as fun f⁶(x) {
-//│   return f_f_g⁰(0, x, undefined)
-//│ };
+//│ define f⁶ as fun f⁷(x) { return f_g¹(0, x) };
 //│ define g⁴ as fun g⁵(x) { return f_g¹(1, x) };
 //│ end
 //│ —————————————————| Output |—————————————————————————————————————————————————————————————————————————
-//│ FAILURE: Unexpected lack of error to fix
 
 // Functions inside module definitions are lifted to the top level. This means they cannot yet be optimized.
 :lift
@@ -354,10 +332,10 @@ module A with
     @tailcall g(x - 1)
 A.f(10000)
 //│ ╔══[COMPILATION ERROR] This tail call exits the current scope and is not optimized.
-//│ ║  l.353: 	    fun g(x) = if x < 0 then 0 else @tailcall f(x)
+//│ ║  l.331: 	    fun g(x) = if x < 0 then 0 else @tailcall f(x)
 //│ ╙──       	                                              ^^^^
 //│ ╔══[COMPILATION ERROR] This tail call exits the current scope and is not optimized.
-//│ ║  l.354: 	    @tailcall g(x - 1)
+//│ ║  l.332: 	    @tailcall g(x - 1)
 //│ ╙──       	              ^^^^^^^^
 //│ = 0
 
@@ -384,12 +362,12 @@ class A with
   fun g(x) = if x == 0 then 1 else @tailcall f(x - 1)
 (new A).f(10)
 //│ ╔══[COMPILATION ERROR] Calls from class methods cannot yet be marked @tailcall.
-//│ ║  l.383: 	  @tailrec fun f(x) = if x == 0 then 0 else @tailcall g(x - 1)
+//│ ║  l.361: 	  @tailrec fun f(x) = if x == 0 then 0 else @tailcall g(x - 1)
 //│ ╙──       	                                                      ^^^^^^^^
 //│ ╔══[COMPILATION ERROR] Class methods may not yet be marked @tailrec.
-//│ ║  l.383: 	  @tailrec fun f(x) = if x == 0 then 0 else @tailcall g(x - 1)
+//│ ║  l.361: 	  @tailrec fun f(x) = if x == 0 then 0 else @tailcall g(x - 1)
 //│ ╙──       	               ^
 //│ ╔══[COMPILATION ERROR] Calls from class methods cannot yet be marked @tailcall.
-//│ ║  l.384: 	  fun g(x) = if x == 0 then 1 else @tailcall f(x - 1)
+//│ ║  l.362: 	  fun g(x) = if x == 0 then 1 else @tailcall f(x - 1)
 //│ ╙──       	                                             ^^^^^^^^
 //│ = 0

From 41e5ff614c263c26caa81795d8effe6f570e992b Mon Sep 17 00:00:00 2001
From: CAG2Mark <git@markng.com>
Date: Thu, 27 Aug 2026 16:35:26 +0800
Subject: [PATCH 04/13] revert hkscratch

---
 hkmc2/shared/src/test/mlscript/HkScratch.mls | 1 -
 1 file changed, 1 deletion(-)

diff --git a/hkmc2/shared/src/test/mlscript/HkScratch.mls b/hkmc2/shared/src/test/mlscript/HkScratch.mls
index ef38e8b363..48d7326643 100644
--- a/hkmc2/shared/src/test/mlscript/HkScratch.mls
+++ b/hkmc2/shared/src/test/mlscript/HkScratch.mls
@@ -9,4 +9,3 @@
 // :todo
 
 
-

From 9f39f6c277ab276adfa645a3e067a9e3a254dfbf Mon Sep 17 00:00:00 2001
From: CAG2Mark <git@markng.com>
Date: Thu, 27 Aug 2026 17:10:11 +0800
Subject: [PATCH 05/13] fix bug and clean up

---
 .../main/scala/hkmc2/codegen/TailRecOpt.scala | 141 ++---
 .../test/mlscript/tailrec/MultiArgLists.mls   | 159 +++---
 .../src/test/mlscript/tailrec/TailRecOpt.mls  |  40 +-
 .../mlscript/ups/examples/HindleyMilner.mls   | 505 +++++++++++++++++-
 4 files changed, 656 insertions(+), 189 deletions(-)

diff --git a/hkmc2/shared/src/main/scala/hkmc2/codegen/TailRecOpt.scala b/hkmc2/shared/src/main/scala/hkmc2/codegen/TailRecOpt.scala
index eadebc7438..f07dc3599a 100644
--- a/hkmc2/shared/src/main/scala/hkmc2/codegen/TailRecOpt.scala
+++ b/hkmc2/shared/src/main/scala/hkmc2/codegen/TailRecOpt.scala
@@ -325,18 +325,28 @@ class TailRecOpt(checkAnnotations: Bool)(using State, TL, Raise):
             :: msg"It could self-recurse through this call, which is not a tail call." -> reportLoc
             :: Nil
           ))
-
+    
+    val (hasWrapper, bms) =
+      if funsLen === 1 then funs.head.params match
+        // Simplest case: One function, one parameter list, no wrapper.
+        case _ :: Nil => (false, funs.head.sym)
+        // When a function has multiple param lists, TailRecOpt flattens them into a single
+        // param list for the internal loop. We need a wrapper function that preserves the
+        // original multi-param-list interface and delegates to the flattened internal loop.
+        case _ => (true, BlockMemberSymbol(funs.head.sym.nme + "$tailrec", Nil, true))
+      // Multiple functions: Create a wrapper.
+      else (true, BlockMemberSymbol(funs.iterator.map(_.sym.nme).mkString("_"), Nil, true))
+    val dSym =
+      if bms is funs.head.sym then funs.head.dSym
+      else TermSymbol(syntax.Fun, owner, Tree.Ident(bms.nme))
+    
     val maxParamLen = maxInt(funs, paramsLen)
     val paramSyms =
-        if funs.length === 1 then
-          val syms = funs.head.paramSyms
-          if funs.head.params.length === 1 then syms
-          else
-            // Duplicate the params for the internal loop defn (see the doc at the
-            // end of this function), but preserve the names.
-            syms.map(v => VarSymbol(Tree.Ident(v.id.name)))
-        else
-          for i <- 0 until maxParamLen yield VarSymbol(Tree.Ident("param" + i))
+        if hasWrapper then 
+          if funsLen === 1 then
+            funs.head.paramSyms.map(v => VarSymbol(Tree.Ident(v.id.name)))
+          else for i <- 0 until maxParamLen yield VarSymbol(Tree.Ident("param" + i))
+        else funs.head.paramSyms
       .toList
     val paramSymsArr = ArrayBuffer.from(paramSyms)
     // Function -> param -> param symbol in the rewritten function
@@ -351,23 +361,27 @@ class TailRecOpt(checkAnnotations: Bool)(using State, TL, Raise):
     
     val dSymIds = funs.iterator.map(_.dSym).zipWithIndex.toMap
     val dSymToDefn = funs.iterator.map(f => f.dSym -> f).toMap
-    val bms =
-      if funsLen === 1 then funs.head.params match
-        case _ :: Nil => funs.head.sym
-        case _ => BlockMemberSymbol(funs.head.sym.nme + "$tailrec", Nil, true)
-      else BlockMemberSymbol(funs.iterator.map(_.sym.nme).mkString("_"), Nil, true)
-    val dSym =
-      if funsLen === 1 then funs.head.params match
-        case _ :: Nil => funs.head.dSym
-        case _ => TermSymbol(syntax.Fun, owner, Tree.Ident(bms.nme))
-      else TermSymbol(syntax.Fun, owner, Tree.Ident(bms.nme))
+
     val loopSym = LabelSymbol(N, "loopLabel")
     val curIdSym = VarSymbol(Tree.Ident("id"))
     
-    val sel = owner match
+    val loopDefnPath = owner match
       case Some(value) => Select(value.asThis, Tree.Ident(bms.nme))(S(dSym))(false)
       case None => bms.asMemberRef(dSym)
     
+    def rewriteKnownCall(callee: FunDefn, flattenedArgs: List[Path]) =
+      if !hasWrapper then lastWords("Tried to rewrite a call to a non-existent loop definition.")
+      if callee.paramSyms.length =/= flattenedArgs.length then lastWords("Incorrect function call arity.")
+      // Fill in the argument list with the arguments in the correct position by applying the paramSym -> arg map to
+      // the loop definitions parameter list.
+      val argsMap = (callee.paramSyms.map(paramSymsMap(callee.dSym)) zip flattenedArgs).toMap
+      val args = paramSyms.map: s =>
+        argsMap.get(s) match
+          case Some(pth) => Arg(N, pth)
+          case None => Arg(N, Value.Lit(Tree.UnitLit(false)))
+      val argsWithId = if funsLen > 1 then Value.Lit(Tree.IntLit(dSymIds(callee.dSym))).asArg :: args else args
+      Call(loopDefnPath, argsWithId ne_:: Nil)(CallMetadata.defaultMlsFun)
+    
     class FunRewriter(f: FunDefn) extends BlockTransformerShallow(SymbolSubst.Id):
       val params = f.paramSyms
       val paramsSet = f.params.toSet
@@ -523,7 +537,7 @@ class TailRecOpt(checkAnnotations: Bool)(using State, TL, Raise):
       // optimizer pass idempotent. Without this, the subsequent tailrec optimizer passes could see the merged and wrapper
       // functions as an SCC and try to rewrite the wrapper's tail call.
       override def applyResult(r: Result)(k: Result => Block): Block = r match
-        case c @ Call(Value.MemberRef(bms, calleeSym: TermSymbol), args) => funsMap.get(calleeSym) match
+        case c @ Call(Value.MemberRef(bms, calleeSym: TermSymbol), args) if hasWrapper => funsMap.get(calleeSym) match
           case Some(callee) if isExactlySaturatedCall(c, callee) =>
             val calleeParamsMap = paramSymsMap(callee.dSym)
             val argListResults = callee.params.zip(c.argss).map:
@@ -533,6 +547,7 @@ class TailRecOpt(checkAnnotations: Bool)(using State, TL, Raise):
             // using this convention. This is because this assumption may not hold in the future, i.e. when arguments could be assigned
             // types for the typed IR.
             var pre = blockBuilder
+            // Create the list of flattened args.
             val argsInOrder: List[Path] = argListResults.flatMap: (ogParams, thisParamSyms, args, argsRes) =>
               argsRes match
                 case CallArgsResult.Success(res) => res.map:
@@ -545,18 +560,7 @@ class TailRecOpt(checkAnnotations: Bool)(using State, TL, Raise):
                   val (initialBlk, paths) = forceSpread(ogParams, args)
                   pre = pre.chain(initialBlk)
                   paths
-            assert(callee.paramSyms.length === argsInOrder.length)
-            val argsMap = (callee.paramSyms.map(paramSymsMap(callee.dSym)) zip argsInOrder).toMap
-            val args = paramSyms.map: s =>
-              argsMap.get(s) match
-                case Some(pth) => Arg(N, pth)
-                case None => Arg(N, Value.Lit(Tree.UnitLit(false)))
-            val argsWithId = if funsLen > 1 then Value.Lit(Tree.IntLit(dSymIds(calleeSym))).asArg :: args else args
-            val call = Call(sel, argsWithId ne_:: Nil)(CallMetadata.defaultMlsFun)
-            pre.rest(k(call))
-            // f.paramSyms
-            // assert(assignmentsInOrder.length === )
-              
+            pre.rest(k(rewriteKnownCall(callee, argsInOrder)))
             
           case _ => super.applyResult(r)(k)
         case _ => super.applyResult(r)(k)
@@ -578,58 +582,31 @@ class TailRecOpt(checkAnnotations: Bool)(using State, TL, Raise):
     
     val loop = Label(loopSym, true, switch, End())
     
-    val rewrittenFuns =
-      if funsLen === 1 then Nil
-      else funs.map: f =>
-        val paramArgs = f.paramSyms.map(s => s.asSimpleRef.asArg)
-        val args =
-          Value.Lit(Tree.IntLit(dSymIds(f.dSym))).asArg
-            :: paramArgs
-            ::: List.fill(maxParamLen - paramArgs.length)(Value.Lit(Tree.UnitLit(false)).asArg)
+    if !hasWrapper then
+      val f = funs.head
+      val defn = FunDefn(
+        owner, bms, dSym,
+        f.params,
+        loop)(N, annotations = f.annotations)
+      (N, defn :: Nil)
+    else
+      val wrappers = funs.map: f =>
+        val paramArgs = f.paramSyms.map(s => s.asSimpleRef)
         val newBod = Return(
-          Call(sel, args ne_:: Nil)(CallMetadata.defaultMlsFun),
+          rewriteKnownCall(f, paramArgs),
         )
         FunDefn(f.owner, f.sym, f.dSym, f.params, newBod)(N, f.annotations)
-    
-    funs match
-      case (f @ FunDefn(params = _ :: Nil | Nil)) :: Nil =>
-        val defn = FunDefn(
-          owner, bms, dSym,
-          f.params,
-          loop)(N, annotations = f.annotations)
-        (N, defn :: Nil)
-      case f :: Nil =>
-        // When a function has multiple param lists, TailRecOpt flattens them into a single
-        // param list for the internal loop. We need a wrapper function that preserves the
-        // original multi-param-list interface and delegates to the flattened internal loop.
-        val params = paramSyms.map(Param.simple(_))
-        
-        val loopAnnots =
-          if f.inline then Annot.Inline :: Annot.Private :: Nil
-          else Annot.Private :: Nil
-        val internalLoopDefn = FunDefn(
-          owner, bms, dSym,
-          PlainParamList(params) :: Nil,
-          loop)(N, annotations = loopAnnots)
-        val paramArgs = f.paramSyms.map(s => s.asSimpleRef.asArg)
-        val wrapperBod = Return(
-          Call(sel, paramArgs ne_:: Nil)(CallMetadata.defaultMlsFun),
-        )
-        val newAnnots = if f.inline then f.annotations else Annot.Inline :: f.annotations
-        val wrapperDefn = FunDefn(f.owner, f.sym, f.dSym, f.params, wrapperBod)(
-          f.configOverride, annotations = newAnnots)
-        (S(internalLoopDefn), wrapperDefn :: Nil)
-      case _ =>
-        val newParamLists =
-          val initial = paramSyms.map(Param.simple(_))
+      val newParamLists =
+        val initial = paramSyms.map(Param.simple(_))
+        if funsLen > 1 then
           PlainParamList(Param.simple(curIdSym) :: initial) :: Nil
-        
-        val loopDefn = FunDefn(
-          owner, bms, dSym,
-          newParamLists,
-          loop)(N, annotations = Nil) // Q: maybe should be Private?
-        
-        (S(loopDefn), rewrittenFuns)
+        else
+          PlainParamList(initial) :: Nil
+      val loopDefn = FunDefn(
+        owner, bms, dSym,
+        newParamLists,
+        loop)(N, annotations = Nil) // Q: maybe should be Private?
+      (S(loopDefn), wrappers)
   
   def optFunctions(fs: List[FunDefn], owner: Opt[InnerSymbol])(using (ScopeData, AccessMap)) =
     val (newFsOpt, fsOpt) = partFns(fs).map(optScc(_, owner)).foldLeft[(List[FunDefn], List[FunDefn])](Nil, Nil):
diff --git a/hkmc2/shared/src/test/mlscript/tailrec/MultiArgLists.mls b/hkmc2/shared/src/test/mlscript/tailrec/MultiArgLists.mls
index 0634683980..5bbceb2fc3 100644
--- a/hkmc2/shared/src/test/mlscript/tailrec/MultiArgLists.mls
+++ b/hkmc2/shared/src/test/mlscript/tailrec/MultiArgLists.mls
@@ -20,7 +20,6 @@ fun loop(x)(y) =
 loop(1000)(0)
 //│ ——————————————| Optimized IR |——————————————————————————————————————————————————————————————————————
 //│ let loop$tailrec;
-//│ @private
 //│ define loop$tailrec as fun loop$tailrec⁰(x, y) {
 //│   loop loopLabel:
 //│     let scrut, tmp, tmp1;
@@ -52,7 +51,6 @@ fun count(start)(stop) =
 count(0)(100)
 //│ ——————————————| Optimized IR |——————————————————————————————————————————————————————————————————————
 //│ let count$tailrec, start, stop, inlinedVal;
-//│ @private
 //│ define count$tailrec as fun count$tailrec⁰(start1, stop1) {
 //│   loop loopLabel:
 //│     let scrut, tmp;
@@ -270,30 +268,32 @@ fun f(a)(...z) = if z is
   [] then a
   [x, ...xs] then f(a + 1)(...xs)
 //│ ——————————————| Optimized IR |——————————————————————————————————————————————————————————————————————
-//│ let f$tailrec;
-//│ @private
-//│ define f$tailrec as fun f$tailrec⁰(a, z) {
-//│   loop loopLabel:
-//│     let tmp;
-//│     match z
-//│       Array(0) =>
-//│         return a
-//│       Array(1+) =>
-//│         let inlinedVal, tmp1;
-//│         do runtime⁰.Tuple⁰.get⁰(z, 0);
-//│         set tmp1 = -¹(z.length﹖, 0);
-//│         set inlinedVal = z.slice﹖(1, tmp1);
-//│         set tmp = +⁰(a, 1);
-//│         set a = tmp;
-//│         set z = inlinedVal;
-//│         continue loopLabel
-//│       else
-//│         throw new globalThis⁰.Error⁰("match error")
-//│     end
-//│   unreachable /* Rest of abortive labelled block */
+//│ define f² as fun f³(a)(...z) {
+//│   let a1, z1, inlinedVal;
+//│   set a1 = a;
+//│   set z1 = z;
+//│   block inlinedLbl:
+//│     loop loopLabel:
+//│       let tmp;
+//│       match z1
+//│         Array(0) =>
+//│           set inlinedVal = a1;
+//│           break inlinedLbl
+//│         Array(1+) =>
+//│           let inlinedVal1, tmp1;
+//│           do runtime⁰.Tuple⁰.get⁰(z1, 0);
+//│           set tmp1 = -¹(z1.length﹖, 0);
+//│           set inlinedVal1 = z1.slice﹖(1, tmp1);
+//│           set tmp = +⁰(a1, 1);
+//│           set a1 = tmp;
+//│           set z1 = inlinedVal1;
+//│           continue loopLabel
+//│         else
+//│           throw new globalThis⁰.Error⁰("match error")
+//│       end
+//│     unreachable /* Rest of abortive labelled block */
+//│   return inlinedVal
 //│ };
-//│ @inline
-//│ define f² as fun f³(a)(...z) { return f$tailrec⁰(a, z) };
 //│ end
 //│ —————————————————| Output |—————————————————————————————————————————————————————————————————————————
 
@@ -308,13 +308,20 @@ f(0)(1, 2, 3, 4)
 fun f(a)(b) = f(a)(b)
 //│ ————————————| Optimized IR Tree |———————————————————————————————————————————————————————————————————
 //│ Program:
-//│   main = Scoped(syms = {member:f$tailrec¹}):
+//│   main = Scoped(syms = {member:f$tailrec⁰}):
 //│     body = Define:
 //│       defn = FunDefn:
-//│         sym = member:f$tailrec¹
-//│         dSym = term:f$tailrec²
+//│         sym = member:f$tailrec⁰
+//│         dSym = term:f$tailrec¹
 //│         params = Ls of
-//│           ParamList: ‹empty›
+//│           ParamList:
+//│             params = Ls of
+//│               Param:
+//│                 sym = a⁰
+//│                 modulefulness = Modulefulness of N
+//│               Param:
+//│                 sym = b⁰
+//│                 modulefulness = Modulefulness of N
 //│         body = Label:
 //│           label = label:loopLabel⁰
 //│           loop = true
@@ -328,19 +335,23 @@ fun f(a)(b) = f(a)(b)
 //│           ParamList:
 //│             params = Ls of
 //│               Param:
-//│                 sym = a⁰
+//│                 sym = a¹
 //│                 modulefulness = Modulefulness of N
 //│           ParamList:
 //│             params = Ls of
 //│               Param:
-//│                 sym = b⁰
+//│                 sym = b¹
 //│                 modulefulness = Modulefulness of N
 //│         body = Return of Call:
-//│           fun = MemberRef{disamb=term:f$tailrec²}:
-//│             bms = member:f$tailrec¹
-//│             disamb = term:f$tailrec²
+//│           fun = MemberRef{disamb=term:f$tailrec¹}:
+//│             bms = member:f$tailrec⁰
+//│             disamb = term:f$tailrec¹
 //│           argss = Ls of
-//│             Nil
+//│             Ls of
+//│               Arg:
+//│                 value = SimpleRef of a¹
+//│               Arg:
+//│                 value = SimpleRef of b¹
 //│ —————————————————| Output |—————————————————————————————————————————————————————————————————————————
 
 
@@ -352,51 +363,28 @@ fun loop(x)(y) =
   else loop(x - 1)(y + x)
 fun f = loop(1000)(0)
 //│ ——————————————| Optimized IR |——————————————————————————————————————————————————————————————————————
+//│ let loop$tailrec;
+//│ define loop$tailrec as fun loop$tailrec¹(x, y) {
+//│   loop loopLabel:
+//│     let scrut, tmp, tmp1;
+//│     set scrut = Predef⁰.equals⁰(x, 0);
+//│     match scrut
+//│       true =>
+//│         return y
+//│       else
+//│         set tmp = -⁰(x, 1);
+//│         set tmp1 = +⁰(y, x);
+//│         set x = tmp;
+//│         set y = tmp1;
+//│         continue loopLabel
+//│     end
+//│   unreachable /* Rest of abortive labelled block */
+//│ };
 //│ @tailrec @inline
 //│ define loop² as fun loop³(x)(y) {
-//│   let x1, y1, inlinedVal;
-//│   set x1 = x;
-//│   set y1 = y;
-//│   block inlinedLbl:
-//│     loop loopLabel:
-//│       let scrut, tmp, tmp1;
-//│       set scrut = Predef⁰.equals⁰(x1, 0);
-//│       match scrut
-//│         true =>
-//│           set inlinedVal = y1;
-//│           break inlinedLbl
-//│         else
-//│           set tmp = -⁰(x1, 1);
-//│           set tmp1 = +⁰(y1, x1);
-//│           set x1 = tmp;
-//│           set y1 = tmp1;
-//│           continue loopLabel
-//│       end
-//│     unreachable /* Rest of abortive labelled block */
-//│   return inlinedVal
-//│ };
-//│ define f⁶ as fun f⁷() {
-//│   let x, y, inlinedVal;
-//│   set x = 1000;
-//│   set y = 0;
-//│   block inlinedLbl:
-//│     loop loopLabel:
-//│       let scrut, tmp, tmp1;
-//│       set scrut = Predef⁰.equals⁰(x, 0);
-//│       match scrut
-//│         true =>
-//│           set inlinedVal = y;
-//│           break inlinedLbl
-//│         else
-//│           set tmp = -⁰(x, 1);
-//│           set tmp1 = +⁰(y, x);
-//│           set x = tmp;
-//│           set y = tmp1;
-//│           continue loopLabel
-//│       end
-//│     unreachable /* Rest of abortive labelled block */
-//│   return inlinedVal
+//│   return loop$tailrec¹(x, y)
 //│ };
+//│ define f⁶ as fun f⁷() { return loop$tailrec¹(1000, 0) };
 //│ end
 //│ —————————————————| Output |—————————————————————————————————————————————————————————————————————————
 
@@ -409,8 +397,7 @@ fun loop(x)(y) =
 loop(5)(5)
 //│ ——————————————| Optimized IR |——————————————————————————————————————————————————————————————————————
 //│ let loop$tailrec;
-//│ @private
-//│ define loop$tailrec as fun loop$tailrec¹(x, y) {
+//│ define loop$tailrec as fun loop$tailrec²(x, y) {
 //│   loop loopLabel:
 //│     let scrut, scrut1, tmp, tmp1, tmp2;
 //│     set scrut = ===⁰(y, 0);
@@ -422,7 +409,7 @@ loop(5)(5)
 //│         match scrut1
 //│           true =>
 //│             set tmp = -⁰(y, 1);
-//│             set tmp1 = loop$tailrec¹(5, tmp);
+//│             set tmp1 = loop$tailrec²(5, tmp);
 //│             return +⁰(1, tmp1)
 //│           else
 //│             set tmp2 = -⁰(x, 1);
@@ -433,8 +420,8 @@ loop(5)(5)
 //│   unreachable /* Rest of abortive labelled block */
 //│ };
 //│ @inline
-//│ define loop⁴ as fun loop⁵(x)(y) { return loop$tailrec¹(x, y) };
-//│ return loop$tailrec¹(5, 5)
+//│ define loop⁴ as fun loop⁵(x)(y) { return loop$tailrec²(x, y) };
+//│ return loop$tailrec²(5, 5)
 //│ —————————————————| Output |—————————————————————————————————————————————————————————————————————————
 //│ = 5
 
@@ -470,8 +457,7 @@ fun f(n)(a)(...z) =
       res
 //│ ——————————————| Optimized IR |——————————————————————————————————————————————————————————————————————
 //│ let f$tailrec;
-//│ @private
-//│ define f$tailrec as fun f$tailrec³(n, a, z) {
+//│ define f$tailrec as fun f$tailrec²(n, a, z) {
 //│   loop loopLabel:
 //│     let scrut, res, tmp, tmp1;
 //│     set scrut = >⁰(n, 0);
@@ -490,7 +476,7 @@ fun f(n)(a)(...z) =
 //│             set tmp2 = -¹(z.length﹖, 0);
 //│             set inlinedVal = z.slice﹖(1, tmp2);
 //│             set tmp1 = +⁰(a, 1);
-//│             set res = f$tailrec³(n, tmp1, inlinedVal);
+//│             set res = f$tailrec²(n, tmp1, inlinedVal);
 //│             do Predef⁰.print⁰("hi!");
 //│             return res
 //│           else
@@ -499,8 +485,7 @@ fun f(n)(a)(...z) =
 //│     end
 //│   unreachable /* Rest of abortive labelled block */
 //│ };
-//│ @inline
-//│ define f⁸ as fun f⁹(n)(a)(...z) { return f$tailrec³(n, a, z) };
+//│ define f⁸ as fun f⁹(n)(a)(...z) { return f$tailrec²(n, a, z) };
 //│ end
 //│ —————————————————| Output |—————————————————————————————————————————————————————————————————————————
 
diff --git a/hkmc2/shared/src/test/mlscript/tailrec/TailRecOpt.mls b/hkmc2/shared/src/test/mlscript/tailrec/TailRecOpt.mls
index c9f59cc8e7..e42a8f9a81 100644
--- a/hkmc2/shared/src/test/mlscript/tailrec/TailRecOpt.mls
+++ b/hkmc2/shared/src/test/mlscript/tailrec/TailRecOpt.mls
@@ -323,6 +323,36 @@ fun g(x) =
 //│ end
 //│ —————————————————| Output |—————————————————————————————————————————————————————————————————————————
 
+// Nothing should be rewritten in the non tail calls
+:soir
+fun f(n, x, ...y) =
+  if n === 0 then [x, y]
+  else
+    f(0, 1, 2, 3)
+    f(0, ...[1, 2, 3])
+    f(0, 1, 2, 3)
+//│ ——————————————| Optimized IR |——————————————————————————————————————————————————————————————————————
+//│ define f⁸ as fun f⁹(n, x, ...y) {
+//│   loop loopLabel:
+//│     let scrut, tmp;
+//│     set scrut = ===⁰(n, 0);
+//│     match scrut
+//│       true =>
+//│         return [x, y]
+//│       else
+//│         do f⁹(0, 1, 2, 3);
+//│         set tmp = [1, 2, 3];
+//│         do f⁹(0, ...tmp);
+//│         set n = 0;
+//│         set x = 1;
+//│         set y = mut [2, 3];
+//│         continue loopLabel
+//│     end
+//│   unreachable /* Rest of abortive labelled block */
+//│ };
+//│ end
+//│ —————————————————| Output |—————————————————————————————————————————————————————————————————————————
+
 // Functions inside module definitions are lifted to the top level. This means they cannot yet be optimized.
 :lift
 :fixme
@@ -332,10 +362,10 @@ module A with
     @tailcall g(x - 1)
 A.f(10000)
 //│ ╔══[COMPILATION ERROR] This tail call exits the current scope and is not optimized.
-//│ ║  l.331: 	    fun g(x) = if x < 0 then 0 else @tailcall f(x)
+//│ ║  l.361: 	    fun g(x) = if x < 0 then 0 else @tailcall f(x)
 //│ ╙──       	                                              ^^^^
 //│ ╔══[COMPILATION ERROR] This tail call exits the current scope and is not optimized.
-//│ ║  l.332: 	    @tailcall g(x - 1)
+//│ ║  l.362: 	    @tailcall g(x - 1)
 //│ ╙──       	              ^^^^^^^^
 //│ = 0
 
@@ -362,12 +392,12 @@ class A with
   fun g(x) = if x == 0 then 1 else @tailcall f(x - 1)
 (new A).f(10)
 //│ ╔══[COMPILATION ERROR] Calls from class methods cannot yet be marked @tailcall.
-//│ ║  l.361: 	  @tailrec fun f(x) = if x == 0 then 0 else @tailcall g(x - 1)
+//│ ║  l.391: 	  @tailrec fun f(x) = if x == 0 then 0 else @tailcall g(x - 1)
 //│ ╙──       	                                                      ^^^^^^^^
 //│ ╔══[COMPILATION ERROR] Class methods may not yet be marked @tailrec.
-//│ ║  l.361: 	  @tailrec fun f(x) = if x == 0 then 0 else @tailcall g(x - 1)
+//│ ║  l.391: 	  @tailrec fun f(x) = if x == 0 then 0 else @tailcall g(x - 1)
 //│ ╙──       	               ^
 //│ ╔══[COMPILATION ERROR] Calls from class methods cannot yet be marked @tailcall.
-//│ ║  l.362: 	  fun g(x) = if x == 0 then 1 else @tailcall f(x - 1)
+//│ ║  l.392: 	  fun g(x) = if x == 0 then 1 else @tailcall f(x - 1)
 //│ ╙──       	                                             ^^^^^^^^
 //│ = 0
diff --git a/hkmc2/shared/src/test/mlscript/ups/examples/HindleyMilner.mls b/hkmc2/shared/src/test/mlscript/ups/examples/HindleyMilner.mls
index b71a15d0ed..1fb2c2bd7e 100644
--- a/hkmc2/shared/src/test/mlscript/ups/examples/HindleyMilner.mls
+++ b/hkmc2/shared/src/test/mlscript/ups/examples/HindleyMilner.mls
@@ -243,15 +243,76 @@ fun infer(env, term)(using gen: Gen) = if term is
     let tv = gen.fresh
     let env1 = env.extend(name, Scheme(new Set([]), tv))
     infer(env1, body) is [s, t] then [s, TFun(s.apply(tv), t)]
+//│ FAILURE: Unexpected exception
+//│ /!!!\ Uncaught error: java.lang.AssertionError: assertion failed
+//│ 	at: scala.runtime.Scala3RunTime$.assertFailed(Scala3RunTime.scala:13)
+//│ 	at: hkmc2.TailRecOpt$FunRewriter$1.applyResult(TailRecOpt.scala:551)
+//│ 	at: hkmc2.codegen.BlockTransformer.applyBlock(BlockTransformer.scala:83)
+//│ 	at: hkmc2.TailRecOpt$FunRewriter$1.applyBlock(TailRecOpt.scala:522)
+//│ 	at: hkmc2.codegen.BlockTransformer.applySubBlock(BlockTransformer.scala:29)
+//│ 	at: hkmc2.codegen.BlockTransformer.applyBlock$$anonfun$4(BlockTransformer.scala:85)
+//│ 	at: hkmc2.codegen.BlockTransformer.applyPath$$anonfun$2(BlockTransformer.scala:190)
+//│ 	at: hkmc2.codegen.BlockTransformer.applyValue(BlockTransformer.scala:196)
+//│ 	at: hkmc2.codegen.BlockTransformer.applyPath(BlockTransformer.scala:191)
+//│ 	at: hkmc2.codegen.BlockTransformer.applyPath(BlockTransformer.scala:188)
 
 // Type inference with generalization
 fun inferTop(env, name, term)(using Gen) =
   if infer(env, term) is [subst, typ] then...
   [subst, env.generalize(typ)]
+//│ FAILURE: Unexpected compilation error
+//│ FAILURE LOCATION: lookup_! (Scope.scala:136)
+//│ FAILURE INFO: Tuple2:
+//│   _1 = Tuple2:
+//│     _1 = member:infer$tailrec⁰
+//│     _2 = class hkmc2.semantics.BlockMemberSymbol
+//│   _2 = Scope:
+//│     parentOrCfg = Right of Scope:
+//│       parentOrCfg = Right of Scope:
+//│         parentOrCfg = Right of Scope:
+//│           parentOrCfg = Left of Cfg:
+//│             escapeChars = true
+//│             useSuperscripts = false
+//│             includeZero = false
+//│             defaultName = "tmp"
+//│           curThis = S of S of globalThis:globalThis⁰
+//│           bindings = HashMap(tmp:runtime -> runtime, tmp:block$res -> block$res12, tmp:definitionMetadata -> definitionMetadata, tmp:prettyPrint -> prettyPrint, tmp:Term -> Term, tmp:Block -> Block, tmp:tmp -> tmp1, tmp:option -> option, tmp:block$res -> block$res13, t1 -> t1, t2 -> t2, tmp:inlinedVal -> inlinedVal, tmp:tmp -> tmp2, tmp:scrut -> scrut, tmp:block$res -> block$res14, tmp:tmp -> tmp3, tmp:tmp -> tmp4, tmp:block$res -> block$res15, tmp:tmp -> tmp5, t2 -> t21, tmp:inlinedVal -> inlinedVal1, member:lambda$ -> lambda$, tmp:block$res -> block$res, tmp:tmp -> tmp6, tmp:scrut -> scrut1, tmp:block$res -> block$res1, tmp:block$res -> block$res16, tmp:block$res -> block$res2, member:Option -> Option, member:Type -> Type1, member:TVar -> TVar1, member:TFun -> TFun1, tmp:tmp -> tmp7, member:TPrim -> TPrim1, tmp:tmp -> tmp8, class:Type -> Type, tmp:tmp -> tmp9, tmp:tmp -> tmp10, tmp:tmp -> tmp11, tmp:tmp -> tmp12, class:TFun -> TFun, tmp:tmp -> tmp13, tmp:block$res -> block$res17, tmp:tmp -> tmp14, tmp:tmp -> tmp15, tmp:tmp -> tmp16, tmp:tmp -> tmp17, tmp:tmp -> tmp18, tmp:tmp -> tmp19, tmp:inlinedVal -> inlinedVal2, tmp:tmp -> tmp20, tmp:scrut -> scrut2, tmp:block$res -> block$res18, tmp:block$res -> block$res7, emptySub -> emptySub, tmp:tmp -> tmp21, tmp:tmp -> tmp22, tmp:tmp -> tmp23, tmp:tmp -> tmp, tmp:tmp -> tmp24, member:Predef -> Predef, tmp:block$res -> block$res8, tmp:block$res -> block$res19, member:applyPattern -> applyPattern, tmp:tmp -> tmp25, tmp:tmp -> tmp26, tmp:tmp -> tmp27, tmp:inlinedVal -> inlinedVal3, tmp:block$res -> block$res9, tmp:tmp -> tmp28, tmp:scrut -> scrut3, member:Unify -> Unify1, tmp:block$res -> block$res20, pattern:Unify -> Unify, member:Env -> Env1, class:Env -> Env, member:Iter -> Iter, class:TVar -> TVar, class:TPrim -> TPrim, member:Runtime -> Runtime, member:inferTop -> inferTop, tmp:block$res -> block$res5, member:Scheme -> Scheme1, class:Scheme -> Scheme, tmp:block$res -> block$res24, tmp:block$res -> block$res10, member:unify' -> unify$_, tmp:block$res -> block$res3, TInt -> TInt, TBool -> TBool, tmp:block$res -> block$res4, member:Term -> Term2, member:IntLit -> IntLit1, member:Var -> Var1, member:App -> App1, tmp:block$res -> block$res11, member:Abs -> Abs1, member:BoolLit -> BoolLit1, member:unify -> unify, member:ShowTerm -> ShowTerm1, pattern:ShowTerm -> ShowTerm, class:Abs -> Abs, class:App -> App, tmp:block$res -> block$res21, emptyEnv -> emptyEnv, tmp:block$res -> block$res6, tmp:tmp -> tmp29, tmp:block$res -> block$res22, member:Subst -> Subst1, class:Subst -> Subst, member:Gen -> Gen1, class:Gen -> Gen, class:Term -> Term1, class:Var -> Var, tmp:block$res -> block$res23, class:IntLit -> IntLit, class:BoolLit -> BoolLit)
+//│           defaultImportBindings = HashMap(/storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Iter.mjs -> Iter, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Option.mjs -> Option, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Runtime.mjs -> Runtime, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Predef.mjs -> Predef)
+//│         curThis = S of N
+//│         bindings = HashMap(env -> env, name -> name, term -> term)
+//│         defaultImportBindings = HashMap()
+//│       bindings = HashMap( -> tmp30)
+//│       defaultImportBindings = HashMap()
+//│     bindings = HashMap(tmp:inlinedVal -> inlinedVal4, tmp:element1$ -> element1$, tmp:element0$ -> element0$, tmp:tmp -> tmp31)
+//│     defaultImportBindings = HashMap()
+//│ ═══[COMPILATION ERROR] No definition found in scope for member 'infer$tailrec'
 
 fun (|-) inferType(env, term) =
   using Gen = new Gen
   env.generalize(infer(env, term).1).show
+//│ FAILURE: Unexpected compilation error
+//│ FAILURE LOCATION: lookup_! (Scope.scala:136)
+//│ FAILURE INFO: Tuple2:
+//│   _1 = Tuple2:
+//│     _1 = member:infer$tailrec⁰
+//│     _2 = class hkmc2.semantics.BlockMemberSymbol
+//│   _2 = Scope:
+//│     parentOrCfg = Right of Scope:
+//│       parentOrCfg = Right of Scope:
+//│         parentOrCfg = Left of Cfg:
+//│           escapeChars = true
+//│           useSuperscripts = false
+//│           includeZero = false
+//│           defaultName = "tmp"
+//│         curThis = S of S of globalThis:globalThis⁰
+//│         bindings = HashMap(tmp:runtime -> runtime, tmp:block$res -> block$res12, tmp:definitionMetadata -> definitionMetadata, tmp:prettyPrint -> prettyPrint, tmp:Term -> Term, tmp:Block -> Block, tmp:tmp -> tmp1, tmp:option -> option, tmp:block$res -> block$res13, t1 -> t1, t2 -> t2, tmp:inlinedVal -> inlinedVal, tmp:tmp -> tmp2, tmp:scrut -> scrut, tmp:block$res -> block$res14, tmp:tmp -> tmp3, tmp:tmp -> tmp4, tmp:block$res -> block$res15, tmp:tmp -> tmp5, t2 -> t21, tmp:inlinedVal -> inlinedVal1, member:lambda$ -> lambda$, tmp:block$res -> block$res, tmp:tmp -> tmp6, tmp:scrut -> scrut1, tmp:block$res -> block$res1, tmp:block$res -> block$res16, tmp:block$res -> block$res2, member:Option -> Option, member:Type -> Type1, member:TVar -> TVar1, member:TFun -> TFun1, tmp:tmp -> tmp7, member:TPrim -> TPrim1, tmp:tmp -> tmp8, class:Type -> Type, tmp:tmp -> tmp9, tmp:tmp -> tmp10, tmp:tmp -> tmp11, tmp:tmp -> tmp12, class:TFun -> TFun, tmp:tmp -> tmp13, tmp:block$res -> block$res17, tmp:tmp -> tmp14, tmp:tmp -> tmp15, tmp:tmp -> tmp16, tmp:tmp -> tmp17, tmp:tmp -> tmp18, tmp:tmp -> tmp19, tmp:inlinedVal -> inlinedVal2, tmp:tmp -> tmp20, tmp:scrut -> scrut2, tmp:block$res -> block$res18, tmp:block$res -> block$res7, emptySub -> emptySub, tmp:tmp -> tmp21, tmp:tmp -> tmp22, tmp:tmp -> tmp23, tmp:tmp -> tmp, tmp:tmp -> tmp24, member:Predef -> Predef, tmp:block$res -> block$res8, tmp:block$res -> block$res19, member:applyPattern -> applyPattern, tmp:tmp -> tmp25, tmp:tmp -> tmp26, tmp:tmp -> tmp27, tmp:inlinedVal -> inlinedVal3, tmp:block$res -> block$res9, tmp:tmp -> tmp28, tmp:scrut -> scrut3, member:Unify -> Unify1, tmp:block$res -> block$res20, pattern:Unify -> Unify, member:Env -> Env1, class:Env -> Env, member:Iter -> Iter, class:TVar -> TVar, class:TPrim -> TPrim, member:Runtime -> Runtime, member:inferTop -> inferTop, tmp:block$res -> block$res5, member:Scheme -> Scheme1, class:Scheme -> Scheme, tmp:block$res -> block$res24, tmp:block$res -> block$res10, member:unify' -> unify$_, member:inferType -> inferType, tmp:block$res -> block$res3, TInt -> TInt, TBool -> TBool, tmp:block$res -> block$res4, member:Term -> Term2, member:IntLit -> IntLit1, member:Var -> Var1, member:App -> App1, tmp:block$res -> block$res11, member:Abs -> Abs1, member:BoolLit -> BoolLit1, member:unify -> unify, member:ShowTerm -> ShowTerm1, pattern:ShowTerm -> ShowTerm, class:Abs -> Abs, tmp:block$res -> block$res25, class:App -> App, tmp:block$res -> block$res21, emptyEnv -> emptyEnv, tmp:block$res -> block$res6, tmp:tmp -> tmp29, tmp:block$res -> block$res22, member:Subst -> Subst1, class:Subst -> Subst, member:Gen -> Gen1, class:Gen -> Gen, class:Term -> Term1, class:Var -> Var, tmp:block$res -> block$res23, class:IntLit -> IntLit, class:BoolLit -> BoolLit)
+//│         defaultImportBindings = HashMap(/storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Iter.mjs -> Iter, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Option.mjs -> Option, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Runtime.mjs -> Runtime, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Predef.mjs -> Predef)
+//│       curThis = S of N
+//│       bindings = HashMap(env -> env, term -> term)
+//│       defaultImportBindings = HashMap()
+//│     bindings = HashMap(member:instance$Ident(Gen) -> instance$Ident$_Gen$_, tmp:tmp -> tmp30, tmp:tmp -> tmp31, tmp:inlinedVal -> inlinedVal4)
+//│     defaultImportBindings = HashMap()
+//│ ═══[COMPILATION ERROR] No definition found in scope for member 'infer$tailrec'
 
 :silent
 // Example terms
@@ -270,32 +331,268 @@ print of compose.show
 //│ > λf. λg. λx. f (g x)
 
 emptyEnv |- id
-//│ = "∀t₀. t₀ -> t₀"
+//│ FAILURE: Unexpected compilation error
+//│ FAILURE LOCATION: lookup_! (Scope.scala:136)
+//│ FAILURE INFO: Tuple2:
+//│   _1 = Tuple2:
+//│     _1 = member:infer$tailrec⁰
+//│     _2 = class hkmc2.semantics.BlockMemberSymbol
+//│   _2 = Scope:
+//│     parentOrCfg = Left of Cfg:
+//│       escapeChars = true
+//│       useSuperscripts = false
+//│       includeZero = false
+//│       defaultName = "tmp"
+//│     curThis = S of S of globalThis:globalThis⁰
+//│     bindings = HashMap(tmp:runtime -> runtime, tmp:block$res -> block$res12, tmp:definitionMetadata -> definitionMetadata, tmp:prettyPrint -> prettyPrint, tmp:Term -> Term, tmp:Block -> Block, tmp:tmp -> tmp1, tmp:option -> option, tmp:block$res -> block$res13, t1 -> t1, t2 -> t2, tmp:inlinedVal -> inlinedVal, tmp:tmp -> tmp2, tmp:scrut -> scrut, tmp:block$res -> block$res14, tmp:tmp -> tmp3, tmp:tmp -> tmp4, tmp:block$res -> block$res15, tmp:tmp -> tmp5, t2 -> t21, tmp:inlinedVal -> inlinedVal1, member:lambda$ -> lambda$, tmp:block$res -> block$res, tmp:tmp -> tmp6, tmp:scrut -> scrut1, tmp:block$res -> block$res1, tmp:block$res -> block$res16, tmp:block$res -> block$res2, member:Option -> Option, member:Type -> Type1, member:TVar -> TVar1, member:TFun -> TFun1, tmp:tmp -> tmp7, member:TPrim -> TPrim1, tmp:tmp -> tmp8, class:Type -> Type, tmp:tmp -> tmp9, tmp:tmp -> tmp10, tmp:tmp -> tmp11, tmp:tmp -> tmp12, class:TFun -> TFun, tmp:tmp -> tmp13, tmp:block$res -> block$res17, tmp:tmp -> tmp14, tmp:tmp -> tmp15, tmp:tmp -> tmp16, tmp:tmp -> tmp17, tmp:tmp -> tmp18, tmp:tmp -> tmp19, tmp:inlinedVal -> inlinedVal2, tmp:tmp -> tmp20, tmp:scrut -> scrut2, tmp:block$res -> block$res18, tmp:block$res -> block$res7, emptySub -> emptySub, tmp:tmp -> tmp21, tmp:tmp -> tmp22, tmp:tmp -> tmp23, tmp:tmp -> tmp, tmp:tmp -> tmp24, member:Predef -> Predef, tmp:block$res -> block$res8, tmp:block$res -> block$res19, member:applyPattern -> applyPattern, tmp:tmp -> tmp25, tmp:tmp -> tmp26, tmp:tmp -> tmp27, tmp:inlinedVal -> inlinedVal3, tmp:block$res -> block$res9, tmp:tmp -> tmp28, tmp:scrut -> scrut3, member:Unify -> Unify1, tmp:block$res -> block$res20, pattern:Unify -> Unify, member:Env -> Env1, class:Env -> Env, member:Iter -> Iter, class:TVar -> TVar, class:TPrim -> TPrim, member:Runtime -> Runtime, member:inferTop -> inferTop, tmp:block$res -> block$res5, member:Scheme -> Scheme1, class:Scheme -> Scheme, tmp:block$res -> block$res24, tmp:block$res -> block$res10, member:unify' -> unify$_, member:inferType -> inferType, tmp:block$res -> block$res3, TInt -> TInt, TBool -> TBool, tmp:block$res -> block$res4, member:Term -> Term2, member:IntLit -> IntLit1, member:Var -> Var1, member:App -> App1, tmp:block$res -> block$res11, member:Abs -> Abs1, member:BoolLit -> BoolLit1, member:unify -> unify, member:ShowTerm -> ShowTerm1, pattern:ShowTerm -> ShowTerm, class:Abs -> Abs, tmp:block$res -> block$res25, id -> id, const -> const1, class:App -> App, tmp:block$res -> block$res21, emptyEnv -> emptyEnv, apply -> apply, tmp:block$res -> block$res6, tmp:tmp -> tmp29, tmp:block$res -> block$res22, compose -> compose, member:Subst -> Subst1, class:Subst -> Subst, member:Gen -> Gen1, class:Gen -> Gen, tmp:tmp -> tmp30, tmp:tmp -> tmp31, tmp:tmp -> tmp32, tmp:tmp -> tmp33, tmp:tmp -> tmp34, tmp:tmp -> tmp35, tmp:tmp -> tmp36, tmp:tmp -> tmp37, tmp:tmp -> tmp38, tmp:tmp -> tmp39, tmp:tmp -> tmp40, class:Term -> Term1, tmp:tmp -> tmp41, tmp:tmp -> tmp42, tmp:tmp -> tmp43, tmp:block$res -> block$res26, class:Var -> Var, tmp:block$res -> block$res27, env -> env, term -> term, tmp:block$res -> block$res23, member:instance$Ident(Gen) -> instance$Ident$_Gen$_, tmp:tmp -> tmp44, class:IntLit -> IntLit, tmp:tmp -> tmp45, tmp:inlinedVal -> inlinedVal4, tmp:block$res -> block$res28, class:BoolLit -> BoolLit)
+//│     defaultImportBindings = HashMap(/storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Iter.mjs -> Iter, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Option.mjs -> Option, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Runtime.mjs -> Runtime, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Predef.mjs -> Predef)
+//│ ═══[COMPILATION ERROR] No definition found in scope for member 'infer$tailrec'
+//│ FAILURE: Unexpected runtime error
+//│ FAILURE LOCATION: mkQuery (JSBackendDiffMaker.scala:259)
+//│ ═══[RUNTIME ERROR] ReferenceError: infer$tailrec is not defined
+//│     at REPL94:1:197
+//│     at ContextifyScript.runInThisContext (node:vm:138:12)
+//│     at defaultEval (node:repl:608:24)
+//│     at REPLEvalInContext (node:repl:691:9)
+//│     at AsyncLocalStorage.run (node:internal/async_local_storage/async_context_frame:66:14)
+//│     at REPLServer.REPLEval [as eval] (node:repl:690:19)
+//│     at REPLServer.onLine (node:repl:828:12)
+//│     at REPLServer.emit (node:events:514:20)
+//│     at [_onLine] [as _onLine] (node:internal/readline/interface:474:12)
+//│     at [_normalWrite] [as _normalWrite] (node:internal/readline/interface:669:18)
 
 emptyEnv |- const
-//│ = "∀t₀, t₁. t₀ -> t₁ -> t₀"
+//│ FAILURE: Unexpected compilation error
+//│ FAILURE LOCATION: lookup_! (Scope.scala:136)
+//│ FAILURE INFO: Tuple2:
+//│   _1 = Tuple2:
+//│     _1 = member:infer$tailrec⁰
+//│     _2 = class hkmc2.semantics.BlockMemberSymbol
+//│   _2 = Scope:
+//│     parentOrCfg = Left of Cfg:
+//│       escapeChars = true
+//│       useSuperscripts = false
+//│       includeZero = false
+//│       defaultName = "tmp"
+//│     curThis = S of S of globalThis:globalThis⁰
+//│     bindings = HashMap(term -> term1, member:instance$Ident(Gen) -> instance$Ident$_Gen$_1, tmp:runtime -> runtime, tmp:block$res -> block$res12, tmp:tmp -> tmp46, tmp:definitionMetadata -> definitionMetadata, tmp:tmp -> tmp47, tmp:prettyPrint -> prettyPrint, tmp:inlinedVal -> inlinedVal5, tmp:Term -> Term, tmp:Block -> Block, tmp:tmp -> tmp1, tmp:block$res -> block$res29, tmp:option -> option, tmp:block$res -> block$res13, t1 -> t1, t2 -> t2, tmp:inlinedVal -> inlinedVal, tmp:tmp -> tmp2, tmp:scrut -> scrut, tmp:block$res -> block$res14, tmp:tmp -> tmp3, tmp:tmp -> tmp4, tmp:block$res -> block$res15, tmp:tmp -> tmp5, t2 -> t21, tmp:inlinedVal -> inlinedVal1, member:lambda$ -> lambda$, tmp:block$res -> block$res, tmp:tmp -> tmp6, tmp:scrut -> scrut1, tmp:block$res -> block$res1, tmp:block$res -> block$res16, tmp:block$res -> block$res2, member:Option -> Option, member:Type -> Type1, member:TVar -> TVar1, member:TFun -> TFun1, tmp:tmp -> tmp7, member:TPrim -> TPrim1, tmp:tmp -> tmp8, class:Type -> Type, tmp:tmp -> tmp9, tmp:tmp -> tmp10, tmp:tmp -> tmp11, tmp:tmp -> tmp12, class:TFun -> TFun, tmp:tmp -> tmp13, tmp:block$res -> block$res17, tmp:tmp -> tmp14, tmp:tmp -> tmp15, tmp:tmp -> tmp16, tmp:tmp -> tmp17, tmp:tmp -> tmp18, tmp:tmp -> tmp19, tmp:inlinedVal -> inlinedVal2, tmp:tmp -> tmp20, tmp:scrut -> scrut2, tmp:block$res -> block$res18, tmp:block$res -> block$res7, emptySub -> emptySub, tmp:tmp -> tmp21, tmp:tmp -> tmp22, tmp:tmp -> tmp23, tmp:tmp -> tmp, tmp:tmp -> tmp24, member:Predef -> Predef, tmp:block$res -> block$res8, tmp:block$res -> block$res19, member:applyPattern -> applyPattern, tmp:tmp -> tmp25, tmp:tmp -> tmp26, tmp:tmp -> tmp27, tmp:inlinedVal -> inlinedVal3, tmp:block$res -> block$res9, tmp:tmp -> tmp28, tmp:scrut -> scrut3, member:Unify -> Unify1, tmp:block$res -> block$res20, pattern:Unify -> Unify, member:Env -> Env1, class:Env -> Env, member:Iter -> Iter, class:TVar -> TVar, class:TPrim -> TPrim, member:Runtime -> Runtime, member:inferTop -> inferTop, tmp:block$res -> block$res5, member:Scheme -> Scheme1, class:Scheme -> Scheme, tmp:block$res -> block$res24, tmp:block$res -> block$res10, member:unify' -> unify$_, member:inferType -> inferType, tmp:block$res -> block$res3, TInt -> TInt, TBool -> TBool, tmp:block$res -> block$res4, member:Term -> Term2, member:IntLit -> IntLit1, member:Var -> Var1, member:App -> App1, tmp:block$res -> block$res11, member:Abs -> Abs1, member:BoolLit -> BoolLit1, member:unify -> unify, member:ShowTerm -> ShowTerm1, pattern:ShowTerm -> ShowTerm, class:Abs -> Abs, tmp:block$res -> block$res25, id -> id, const -> const1, class:App -> App, tmp:block$res -> block$res21, emptyEnv -> emptyEnv, apply -> apply, tmp:block$res -> block$res6, tmp:tmp -> tmp29, tmp:block$res -> block$res22, compose -> compose, member:Subst -> Subst1, class:Subst -> Subst, member:Gen -> Gen1, class:Gen -> Gen, tmp:tmp -> tmp30, tmp:tmp -> tmp31, tmp:tmp -> tmp32, tmp:tmp -> tmp33, tmp:tmp -> tmp34, tmp:tmp -> tmp35, tmp:tmp -> tmp36, tmp:tmp -> tmp37, tmp:tmp -> tmp38, tmp:tmp -> tmp39, tmp:tmp -> tmp40, class:Term -> Term1, tmp:tmp -> tmp41, tmp:tmp -> tmp42, tmp:tmp -> tmp43, tmp:block$res -> block$res26, class:Var -> Var, tmp:block$res -> block$res27, env -> env, term -> term, tmp:block$res -> block$res23, member:instance$Ident(Gen) -> instance$Ident$_Gen$_, tmp:tmp -> tmp44, class:IntLit -> IntLit, tmp:tmp -> tmp45, tmp:inlinedVal -> inlinedVal4, tmp:block$res -> block$res28, class:BoolLit -> BoolLit, env -> env1)
+//│     defaultImportBindings = HashMap(/storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Iter.mjs -> Iter, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Option.mjs -> Option, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Runtime.mjs -> Runtime, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Predef.mjs -> Predef)
+//│ ═══[COMPILATION ERROR] No definition found in scope for member 'infer$tailrec'
+//│ FAILURE: Unexpected runtime error
+//│ FAILURE LOCATION: mkQuery (JSBackendDiffMaker.scala:259)
+//│ ═══[RUNTIME ERROR] ReferenceError: infer$tailrec is not defined
+//│     at REPL97:1:207
+//│     at ContextifyScript.runInThisContext (node:vm:138:12)
+//│     at defaultEval (node:repl:608:24)
+//│     at REPLEvalInContext (node:repl:691:9)
+//│     at AsyncLocalStorage.run (node:internal/async_local_storage/async_context_frame:66:14)
+//│     at REPLServer.REPLEval [as eval] (node:repl:690:19)
+//│     at REPLServer.onLine (node:repl:828:12)
+//│     at REPLServer.emit (node:events:514:20)
+//│     at [_onLine] [as _onLine] (node:internal/readline/interface:474:12)
+//│     at [_normalWrite] [as _normalWrite] (node:internal/readline/interface:669:18)
 
 emptyEnv |- apply
-//│ = "∀t₁, t₂. (t₁ -> t₂) -> t₁ -> t₂"
+//│ FAILURE: Unexpected compilation error
+//│ FAILURE LOCATION: lookup_! (Scope.scala:136)
+//│ FAILURE INFO: Tuple2:
+//│   _1 = Tuple2:
+//│     _1 = member:infer$tailrec⁰
+//│     _2 = class hkmc2.semantics.BlockMemberSymbol
+//│   _2 = Scope:
+//│     parentOrCfg = Left of Cfg:
+//│       escapeChars = true
+//│       useSuperscripts = false
+//│       includeZero = false
+//│       defaultName = "tmp"
+//│     curThis = S of S of globalThis:globalThis⁰
+//│     bindings = HashMap(term -> term1, member:instance$Ident(Gen) -> instance$Ident$_Gen$_1, tmp:runtime -> runtime, tmp:block$res -> block$res12, tmp:tmp -> tmp46, tmp:definitionMetadata -> definitionMetadata, tmp:tmp -> tmp47, tmp:prettyPrint -> prettyPrint, tmp:inlinedVal -> inlinedVal5, tmp:Term -> Term, tmp:Block -> Block, tmp:tmp -> tmp1, tmp:block$res -> block$res29, tmp:option -> option, tmp:block$res -> block$res13, env -> env2, term -> term2, t1 -> t1, t2 -> t2, member:instance$Ident(Gen) -> instance$Ident$_Gen$_2, tmp:inlinedVal -> inlinedVal, tmp:tmp -> tmp48, tmp:tmp -> tmp49, tmp:tmp -> tmp2, tmp:inlinedVal -> inlinedVal6, tmp:scrut -> scrut, tmp:block$res -> block$res14, tmp:block$res -> block$res30, tmp:tmp -> tmp3, tmp:tmp -> tmp4, tmp:block$res -> block$res15, tmp:tmp -> tmp5, t2 -> t21, tmp:inlinedVal -> inlinedVal1, member:lambda$ -> lambda$, tmp:block$res -> block$res, tmp:tmp -> tmp6, tmp:scrut -> scrut1, tmp:block$res -> block$res1, tmp:block$res -> block$res16, tmp:block$res -> block$res2, member:Option -> Option, member:Type -> Type1, member:TVar -> TVar1, member:TFun -> TFun1, tmp:tmp -> tmp7, member:TPrim -> TPrim1, tmp:tmp -> tmp8, class:Type -> Type, tmp:tmp -> tmp9, tmp:tmp -> tmp10, tmp:tmp -> tmp11, tmp:tmp -> tmp12, class:TFun -> TFun, tmp:tmp -> tmp13, tmp:block$res -> block$res17, tmp:tmp -> tmp14, tmp:tmp -> tmp15, tmp:tmp -> tmp16, tmp:tmp -> tmp17, tmp:tmp -> tmp18, tmp:tmp -> tmp19, tmp:inlinedVal -> inlinedVal2, tmp:tmp -> tmp20, tmp:scrut -> scrut2, tmp:block$res -> block$res18, tmp:block$res -> block$res7, emptySub -> emptySub, tmp:tmp -> tmp21, tmp:tmp -> tmp22, tmp:tmp -> tmp23, tmp:tmp -> tmp, tmp:tmp -> tmp24, member:Predef -> Predef, tmp:block$res -> block$res8, tmp:block$res -> block$res19, member:applyPattern -> applyPattern, tmp:tmp -> tmp25, tmp:tmp -> tmp26, tmp:tmp -> tmp27, tmp:inlinedVal -> inlinedVal3, tmp:block$res -> block$res9, tmp:tmp -> tmp28, tmp:scrut -> scrut3, member:Unify -> Unify1, tmp:block$res -> block$res20, pattern:Unify -> Unify, member:Env -> Env1, class:Env -> Env, member:Iter -> Iter, class:TVar -> TVar, class:TPrim -> TPrim, member:Runtime -> Runtime, member:inferTop -> inferTop, tmp:block$res -> block$res5, member:Scheme -> Scheme1, class:Scheme -> Scheme, tmp:block$res -> block$res24, tmp:block$res -> block$res10, member:unify' -> unify$_, member:inferType -> inferType, tmp:block$res -> block$res3, TInt -> TInt, TBool -> TBool, tmp:block$res -> block$res4, member:Term -> Term2, member:IntLit -> IntLit1, member:Var -> Var1, member:App -> App1, tmp:block$res -> block$res11, member:Abs -> Abs1, member:BoolLit -> BoolLit1, member:unify -> unify, member:ShowTerm -> ShowTerm1, pattern:ShowTerm -> ShowTerm, class:Abs -> Abs, tmp:block$res -> block$res25, id -> id, const -> const1, class:App -> App, tmp:block$res -> block$res21, emptyEnv -> emptyEnv, apply -> apply, tmp:block$res -> block$res6, tmp:tmp -> tmp29, tmp:block$res -> block$res22, compose -> compose, member:Subst -> Subst1, class:Subst -> Subst, member:Gen -> Gen1, class:Gen -> Gen, tmp:tmp -> tmp30, tmp:tmp -> tmp31, tmp:tmp -> tmp32, tmp:tmp -> tmp33, tmp:tmp -> tmp34, tmp:tmp -> tmp35, tmp:tmp -> tmp36, tmp:tmp -> tmp37, tmp:tmp -> tmp38, tmp:tmp -> tmp39, tmp:tmp -> tmp40, class:Term -> Term1, tmp:tmp -> tmp41, tmp:tmp -> tmp42, tmp:tmp -> tmp43, tmp:block$res -> block$res26, class:Var -> Var, tmp:block$res -> block$res27, env -> env, term -> term, tmp:block$res -> block$res23, member:instance$Ident(Gen) -> instance$Ident$_Gen$_, tmp:tmp -> tmp44, class:IntLit -> IntLit, tmp:tmp -> tmp45, tmp:inlinedVal -> inlinedVal4, tmp:block$res -> block$res28, class:BoolLit -> BoolLit, env -> env1)
+//│     defaultImportBindings = HashMap(/storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Iter.mjs -> Iter, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Option.mjs -> Option, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Runtime.mjs -> Runtime, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Predef.mjs -> Predef)
+//│ ═══[COMPILATION ERROR] No definition found in scope for member 'infer$tailrec'
+//│ FAILURE: Unexpected runtime error
+//│ FAILURE LOCATION: mkQuery (JSBackendDiffMaker.scala:259)
+//│ ═══[RUNTIME ERROR] ReferenceError: infer$tailrec is not defined
+//│     at REPL100:1:206
+//│     at ContextifyScript.runInThisContext (node:vm:138:12)
+//│     at defaultEval (node:repl:608:24)
+//│     at REPLEvalInContext (node:repl:691:9)
+//│     at AsyncLocalStorage.run (node:internal/async_local_storage/async_context_frame:66:14)
+//│     at REPLServer.REPLEval [as eval] (node:repl:690:19)
+//│     at REPLServer.onLine (node:repl:828:12)
+//│     at REPLServer.emit (node:events:514:20)
+//│     at [_onLine] [as _onLine] (node:internal/readline/interface:474:12)
+//│     at [_normalWrite] [as _normalWrite] (node:internal/readline/interface:669:18)
 
 emptyEnv |- compose
-//│ = "∀t₃, t₄, t₂. (t₃ -> t₄) -> (t₂ -> t₃) -> t₂ -> t₄"
+//│ FAILURE: Unexpected compilation error
+//│ FAILURE LOCATION: lookup_! (Scope.scala:136)
+//│ FAILURE INFO: Tuple2:
+//│   _1 = Tuple2:
+//│     _1 = member:infer$tailrec⁰
+//│     _2 = class hkmc2.semantics.BlockMemberSymbol
+//│   _2 = Scope:
+//│     parentOrCfg = Left of Cfg:
+//│       escapeChars = true
+//│       useSuperscripts = false
+//│       includeZero = false
+//│       defaultName = "tmp"
+//│     curThis = S of S of globalThis:globalThis⁰
+//│     bindings = HashMap(term -> term1, member:instance$Ident(Gen) -> instance$Ident$_Gen$_1, tmp:runtime -> runtime, tmp:block$res -> block$res12, tmp:tmp -> tmp46, tmp:definitionMetadata -> definitionMetadata, tmp:tmp -> tmp47, tmp:prettyPrint -> prettyPrint, tmp:inlinedVal -> inlinedVal5, tmp:Term -> Term, tmp:Block -> Block, tmp:tmp -> tmp1, tmp:block$res -> block$res29, tmp:option -> option, tmp:block$res -> block$res13, env -> env2, term -> term2, t1 -> t1, t2 -> t2, member:instance$Ident(Gen) -> instance$Ident$_Gen$_2, tmp:inlinedVal -> inlinedVal, tmp:tmp -> tmp48, tmp:tmp -> tmp49, tmp:tmp -> tmp2, tmp:inlinedVal -> inlinedVal6, tmp:scrut -> scrut, tmp:block$res -> block$res14, tmp:block$res -> block$res30, env -> env3, term -> term3, tmp:tmp -> tmp3, tmp:tmp -> tmp4, tmp:block$res -> block$res15, member:instance$Ident(Gen) -> instance$Ident$_Gen$_3, tmp:tmp -> tmp50, tmp:tmp -> tmp51, tmp:inlinedVal -> inlinedVal7, tmp:tmp -> tmp5, tmp:block$res -> block$res31, t2 -> t21, tmp:inlinedVal -> inlinedVal1, member:lambda$ -> lambda$, tmp:block$res -> block$res, tmp:tmp -> tmp6, tmp:scrut -> scrut1, tmp:block$res -> block$res1, tmp:block$res -> block$res16, tmp:block$res -> block$res2, member:Option -> Option, member:Type -> Type1, member:TVar -> TVar1, member:TFun -> TFun1, tmp:tmp -> tmp7, member:TPrim -> TPrim1, tmp:tmp -> tmp8, class:Type -> Type, tmp:tmp -> tmp9, tmp:tmp -> tmp10, tmp:tmp -> tmp11, tmp:tmp -> tmp12, class:TFun -> TFun, tmp:tmp -> tmp13, tmp:block$res -> block$res17, tmp:tmp -> tmp14, tmp:tmp -> tmp15, tmp:tmp -> tmp16, tmp:tmp -> tmp17, tmp:tmp -> tmp18, tmp:tmp -> tmp19, tmp:inlinedVal -> inlinedVal2, tmp:tmp -> tmp20, tmp:scrut -> scrut2, tmp:block$res -> block$res18, tmp:block$res -> block$res7, emptySub -> emptySub, tmp:tmp -> tmp21, tmp:tmp -> tmp22, tmp:tmp -> tmp23, tmp:tmp -> tmp, tmp:tmp -> tmp24, member:Predef -> Predef, tmp:block$res -> block$res8, tmp:block$res -> block$res19, member:applyPattern -> applyPattern, tmp:tmp -> tmp25, tmp:tmp -> tmp26, tmp:tmp -> tmp27, tmp:inlinedVal -> inlinedVal3, tmp:block$res -> block$res9, tmp:tmp -> tmp28, tmp:scrut -> scrut3, member:Unify -> Unify1, tmp:block$res -> block$res20, pattern:Unify -> Unify, member:Env -> Env1, class:Env -> Env, member:Iter -> Iter, class:TVar -> TVar, class:TPrim -> TPrim, member:Runtime -> Runtime, member:inferTop -> inferTop, tmp:block$res -> block$res5, member:Scheme -> Scheme1, class:Scheme -> Scheme, tmp:block$res -> block$res24, tmp:block$res -> block$res10, member:unify' -> unify$_, member:inferType -> inferType, tmp:block$res -> block$res3, TInt -> TInt, TBool -> TBool, tmp:block$res -> block$res4, member:Term -> Term2, member:IntLit -> IntLit1, member:Var -> Var1, member:App -> App1, tmp:block$res -> block$res11, member:Abs -> Abs1, member:BoolLit -> BoolLit1, member:unify -> unify, member:ShowTerm -> ShowTerm1, pattern:ShowTerm -> ShowTerm, class:Abs -> Abs, tmp:block$res -> block$res25, id -> id, const -> const1, class:App -> App, tmp:block$res -> block$res21, emptyEnv -> emptyEnv, apply -> apply, tmp:block$res -> block$res6, tmp:tmp -> tmp29, tmp:block$res -> block$res22, compose -> compose, member:Subst -> Subst1, class:Subst -> Subst, member:Gen -> Gen1, class:Gen -> Gen, tmp:tmp -> tmp30, tmp:tmp -> tmp31, tmp:tmp -> tmp32, tmp:tmp -> tmp33, tmp:tmp -> tmp34, tmp:tmp -> tmp35, tmp:tmp -> tmp36, tmp:tmp -> tmp37, tmp:tmp -> tmp38, tmp:tmp -> tmp39, tmp:tmp -> tmp40, class:Term -> Term1, tmp:tmp -> tmp41, tmp:tmp -> tmp42, tmp:tmp -> tmp43, tmp:block$res -> block$res26, class:Var -> Var, tmp:block$res -> block$res27, env -> env, term -> term, tmp:block$res -> block$res23, member:instance$Ident(Gen) -> instance$Ident$_Gen$_, tmp:tmp -> tmp44, class:IntLit -> IntLit, tmp:tmp -> tmp45, tmp:inlinedVal -> inlinedVal4, tmp:block$res -> block$res28, class:BoolLit -> BoolLit, env -> env1)
+//│     defaultImportBindings = HashMap(/storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Iter.mjs -> Iter, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Option.mjs -> Option, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Runtime.mjs -> Runtime, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Predef.mjs -> Predef)
+//│ ═══[COMPILATION ERROR] No definition found in scope for member 'infer$tailrec'
+//│ FAILURE: Unexpected runtime error
+//│ FAILURE LOCATION: mkQuery (JSBackendDiffMaker.scala:259)
+//│ ═══[RUNTIME ERROR] ReferenceError: infer$tailrec is not defined
+//│     at REPL103:1:208
+//│     at ContextifyScript.runInThisContext (node:vm:138:12)
+//│     at defaultEval (node:repl:608:24)
+//│     at REPLEvalInContext (node:repl:691:9)
+//│     at AsyncLocalStorage.run (node:internal/async_local_storage/async_context_frame:66:14)
+//│     at REPLServer.REPLEval [as eval] (node:repl:690:19)
+//│     at REPLServer.onLine (node:repl:828:12)
+//│     at REPLServer.emit (node:events:514:20)
+//│     at [_onLine] [as _onLine] (node:internal/readline/interface:474:12)
+//│     at [_normalWrite] [as _normalWrite] (node:internal/readline/interface:669:18)
 
 :expect "Int"
 emptyEnv |- IntLit(42)
-//│ = "Int"
+//│ FAILURE: Unexpected compilation error
+//│ FAILURE LOCATION: lookup_! (Scope.scala:136)
+//│ FAILURE INFO: Tuple2:
+//│   _1 = Tuple2:
+//│     _1 = member:infer$tailrec⁰
+//│     _2 = class hkmc2.semantics.BlockMemberSymbol
+//│   _2 = Scope:
+//│     parentOrCfg = Left of Cfg:
+//│       escapeChars = true
+//│       useSuperscripts = false
+//│       includeZero = false
+//│       defaultName = "tmp"
+//│     curThis = S of S of globalThis:globalThis⁰
+//│     bindings = HashMap(term -> term1, member:instance$Ident(Gen) -> instance$Ident$_Gen$_1, tmp:runtime -> runtime, tmp:block$res -> block$res12, tmp:tmp -> tmp46, tmp:definitionMetadata -> definitionMetadata, tmp:tmp -> tmp47, tmp:prettyPrint -> prettyPrint, tmp:inlinedVal -> inlinedVal5, tmp:Term -> Term, tmp:Block -> Block, tmp:tmp -> tmp1, tmp:block$res -> block$res29, tmp:option -> option, tmp:block$res -> block$res13, env -> env2, term -> term2, t1 -> t1, t2 -> t2, member:instance$Ident(Gen) -> instance$Ident$_Gen$_2, tmp:inlinedVal -> inlinedVal, tmp:tmp -> tmp48, tmp:tmp -> tmp49, tmp:tmp -> tmp2, tmp:inlinedVal -> inlinedVal6, tmp:scrut -> scrut, tmp:block$res -> block$res14, tmp:block$res -> block$res30, env -> env3, term -> term3, tmp:tmp -> tmp3, tmp:tmp -> tmp4, tmp:block$res -> block$res15, member:instance$Ident(Gen) -> instance$Ident$_Gen$_3, tmp:tmp -> tmp50, tmp:tmp -> tmp51, tmp:inlinedVal -> inlinedVal7, tmp:tmp -> tmp5, tmp:block$res -> block$res31, t2 -> t21, tmp:inlinedVal -> inlinedVal1, member:lambda$ -> lambda$, tmp:tmp -> tmp52, env -> env4, tmp:block$res -> block$res, tmp:tmp -> tmp6, tmp:scrut -> scrut1, tmp:block$res -> block$res1, tmp:block$res -> block$res16, member:instance$Ident(Gen) -> instance$Ident$_Gen$_4, tmp:block$res -> block$res2, tmp:tmp -> tmp53, tmp:tmp -> tmp54, tmp:inlinedVal -> inlinedVal8, member:Option -> Option, tmp:block$res -> block$res32, member:Type -> Type1, member:TVar -> TVar1, member:TFun -> TFun1, tmp:tmp -> tmp7, member:TPrim -> TPrim1, tmp:tmp -> tmp8, class:Type -> Type, tmp:tmp -> tmp9, tmp:tmp -> tmp10, tmp:tmp -> tmp11, tmp:tmp -> tmp12, class:TFun -> TFun, tmp:tmp -> tmp13, tmp:block$res -> block$res17, tmp:tmp -> tmp14, tmp:tmp -> tmp15, tmp:tmp -> tmp16, tmp:tmp -> tmp17, tmp:tmp -> tmp18, tmp:tmp -> tmp19, tmp:inlinedVal -> inlinedVal2, tmp:tmp -> tmp20, tmp:scrut -> scrut2, tmp:block$res -> block$res18, tmp:block$res -> block$res7, emptySub -> emptySub, tmp:tmp -> tmp21, tmp:tmp -> tmp22, tmp:tmp -> tmp23, tmp:tmp -> tmp, tmp:tmp -> tmp24, member:Predef -> Predef, tmp:block$res -> block$res8, tmp:block$res -> block$res19, member:applyPattern -> applyPattern, tmp:tmp -> tmp25, tmp:tmp -> tmp26, tmp:tmp -> tmp27, tmp:inlinedVal -> inlinedVal3, tmp:block$res -> block$res9, tmp:tmp -> tmp28, tmp:scrut -> scrut3, member:Unify -> Unify1, tmp:block$res -> block$res20, pattern:Unify -> Unify, member:Env -> Env1, class:Env -> Env, member:Iter -> Iter, class:TVar -> TVar, class:TPrim -> TPrim, member:Runtime -> Runtime, member:inferTop -> inferTop, tmp:block$res -> block$res5, member:Scheme -> Scheme1, class:Scheme -> Scheme, tmp:block$res -> block$res24, tmp:block$res -> block$res10, member:unify' -> unify$_, member:inferType -> inferType, tmp:block$res -> block$res3, TInt -> TInt, TBool -> TBool, tmp:block$res -> block$res4, member:Term -> Term2, member:IntLit -> IntLit1, member:Var -> Var1, member:App -> App1, tmp:block$res -> block$res11, member:Abs -> Abs1, member:BoolLit -> BoolLit1, member:unify -> unify, member:ShowTerm -> ShowTerm1, pattern:ShowTerm -> ShowTerm, class:Abs -> Abs, tmp:block$res -> block$res25, id -> id, const -> const1, class:App -> App, tmp:block$res -> block$res21, emptyEnv -> emptyEnv, apply -> apply, tmp:block$res -> block$res6, tmp:tmp -> tmp29, tmp:block$res -> block$res22, compose -> compose, member:Subst -> Subst1, class:Subst -> Subst, member:Gen -> Gen1, class:Gen -> Gen, tmp:tmp -> tmp30, tmp:tmp -> tmp31, tmp:tmp -> tmp32, tmp:tmp -> tmp33, tmp:tmp -> tmp34, tmp:tmp -> tmp35, tmp:tmp -> tmp36, tmp:tmp -> tmp37, tmp:tmp -> tmp38, tmp:tmp -> tmp39, tmp:tmp -> tmp40, class:Term -> Term1, tmp:tmp -> tmp41, tmp:tmp -> tmp42, tmp:tmp -> tmp43, tmp:block$res -> block$res26, class:Var -> Var, tmp:block$res -> block$res27, env -> env, term -> term, tmp:block$res -> block$res23, member:instance$Ident(Gen) -> instance$Ident$_Gen$_, tmp:tmp -> tmp44, class:IntLit -> IntLit, tmp:tmp -> tmp45, tmp:inlinedVal -> inlinedVal4, tmp:block$res -> block$res28, class:BoolLit -> BoolLit, env -> env1)
+//│     defaultImportBindings = HashMap(/storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Iter.mjs -> Iter, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Option.mjs -> Option, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Runtime.mjs -> Runtime, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Predef.mjs -> Predef)
+//│ ═══[COMPILATION ERROR] No definition found in scope for member 'infer$tailrec'
+//│ FAILURE: Unexpected runtime error
+//│ FAILURE LOCATION: mkQuery (JSBackendDiffMaker.scala:259)
+//│ ═══[RUNTIME ERROR] ReferenceError: infer$tailrec is not defined
+//│     at REPL106:1:231
+//│     at ContextifyScript.runInThisContext (node:vm:138:12)
+//│     at defaultEval (node:repl:608:24)
+//│     at REPLEvalInContext (node:repl:691:9)
+//│     at AsyncLocalStorage.run (node:internal/async_local_storage/async_context_frame:66:14)
+//│     at REPLServer.REPLEval [as eval] (node:repl:690:19)
+//│     at REPLServer.onLine (node:repl:828:12)
+//│     at REPLServer.emit (node:events:514:20)
+//│     at [_onLine] [as _onLine] (node:internal/readline/interface:474:12)
+//│     at [_normalWrite] [as _normalWrite] (node:internal/readline/interface:669:18)
+//│ FAILURE: Unexpected runtime error
+//│ FAILURE LOCATION: processIRBlock (JSBackendDiffMaker.scala:299)
+//│ ═══[RUNTIME ERROR] Expected: '"Int"', got: 'undefined'
 
 :expect "Bool"
 emptyEnv |- BoolLit(true)
-//│ = "Bool"
+//│ FAILURE: Unexpected compilation error
+//│ FAILURE LOCATION: lookup_! (Scope.scala:136)
+//│ FAILURE INFO: Tuple2:
+//│   _1 = Tuple2:
+//│     _1 = member:infer$tailrec⁰
+//│     _2 = class hkmc2.semantics.BlockMemberSymbol
+//│   _2 = Scope:
+//│     parentOrCfg = Left of Cfg:
+//│       escapeChars = true
+//│       useSuperscripts = false
+//│       includeZero = false
+//│       defaultName = "tmp"
+//│     curThis = S of S of globalThis:globalThis⁰
+//│     bindings = HashMap(term -> term1, member:instance$Ident(Gen) -> instance$Ident$_Gen$_1, tmp:runtime -> runtime, tmp:block$res -> block$res12, tmp:tmp -> tmp46, tmp:definitionMetadata -> definitionMetadata, tmp:tmp -> tmp47, tmp:prettyPrint -> prettyPrint, tmp:inlinedVal -> inlinedVal5, tmp:Term -> Term, tmp:Block -> Block, tmp:tmp -> tmp1, tmp:block$res -> block$res29, tmp:option -> option, tmp:block$res -> block$res13, env -> env2, term -> term2, t1 -> t1, t2 -> t2, member:instance$Ident(Gen) -> instance$Ident$_Gen$_2, tmp:inlinedVal -> inlinedVal, tmp:tmp -> tmp48, tmp:tmp -> tmp49, tmp:tmp -> tmp2, tmp:inlinedVal -> inlinedVal6, tmp:scrut -> scrut, tmp:block$res -> block$res14, tmp:block$res -> block$res30, env -> env3, term -> term3, tmp:tmp -> tmp3, tmp:tmp -> tmp4, tmp:block$res -> block$res15, member:instance$Ident(Gen) -> instance$Ident$_Gen$_3, tmp:tmp -> tmp50, tmp:tmp -> tmp51, tmp:inlinedVal -> inlinedVal7, tmp:tmp -> tmp5, tmp:block$res -> block$res31, t2 -> t21, tmp:inlinedVal -> inlinedVal1, member:lambda$ -> lambda$, tmp:tmp -> tmp52, env -> env4, tmp:block$res -> block$res, tmp:tmp -> tmp6, tmp:scrut -> scrut1, tmp:block$res -> block$res1, tmp:block$res -> block$res16, member:instance$Ident(Gen) -> instance$Ident$_Gen$_4, tmp:block$res -> block$res2, tmp:tmp -> tmp53, tmp:tmp -> tmp54, tmp:inlinedVal -> inlinedVal8, member:Option -> Option, tmp:block$res -> block$res32, member:Type -> Type1, member:TVar -> TVar1, member:TFun -> TFun1, tmp:tmp -> tmp7, tmp:tmp -> tmp55, member:TPrim -> TPrim1, tmp:tmp -> tmp8, env -> env5, class:Type -> Type, tmp:tmp -> tmp9, tmp:tmp -> tmp10, tmp:tmp -> tmp11, tmp:tmp -> tmp12, member:instance$Ident(Gen) -> instance$Ident$_Gen$_5, class:TFun -> TFun, tmp:tmp -> tmp13, tmp:tmp -> tmp56, tmp:block$res -> block$res17, tmp:tmp -> tmp57, tmp:inlinedVal -> inlinedVal9, tmp:block$res -> block$res33, tmp:tmp -> tmp14, tmp:tmp -> tmp15, tmp:tmp -> tmp16, tmp:tmp -> tmp17, tmp:tmp -> tmp18, tmp:tmp -> tmp19, tmp:inlinedVal -> inlinedVal2, tmp:tmp -> tmp20, tmp:scrut -> scrut2, tmp:block$res -> block$res18, tmp:block$res -> block$res7, emptySub -> emptySub, tmp:tmp -> tmp21, tmp:tmp -> tmp22, tmp:tmp -> tmp23, tmp:tmp -> tmp, tmp:tmp -> tmp24, member:Predef -> Predef, tmp:block$res -> block$res8, tmp:block$res -> block$res19, member:applyPattern -> applyPattern, tmp:tmp -> tmp25, tmp:tmp -> tmp26, tmp:tmp -> tmp27, tmp:inlinedVal -> inlinedVal3, tmp:block$res -> block$res9, tmp:tmp -> tmp28, tmp:scrut -> scrut3, member:Unify -> Unify1, tmp:block$res -> block$res20, pattern:Unify -> Unify, member:Env -> Env1, class:Env -> Env, member:Iter -> Iter, class:TVar -> TVar, class:TPrim -> TPrim, member:Runtime -> Runtime, member:inferTop -> inferTop, tmp:block$res -> block$res5, member:Scheme -> Scheme1, class:Scheme -> Scheme, tmp:block$res -> block$res24, tmp:block$res -> block$res10, member:unify' -> unify$_, member:inferType -> inferType, tmp:block$res -> block$res3, TInt -> TInt, TBool -> TBool, tmp:block$res -> block$res4, member:Term -> Term2, member:IntLit -> IntLit1, member:Var -> Var1, member:App -> App1, tmp:block$res -> block$res11, member:Abs -> Abs1, member:BoolLit -> BoolLit1, member:unify -> unify, member:ShowTerm -> ShowTerm1, pattern:ShowTerm -> ShowTerm, class:Abs -> Abs, tmp:block$res -> block$res25, id -> id, const -> const1, class:App -> App, tmp:block$res -> block$res21, emptyEnv -> emptyEnv, apply -> apply, tmp:block$res -> block$res6, tmp:tmp -> tmp29, tmp:block$res -> block$res22, compose -> compose, member:Subst -> Subst1, class:Subst -> Subst, member:Gen -> Gen1, class:Gen -> Gen, tmp:tmp -> tmp30, tmp:tmp -> tmp31, tmp:tmp -> tmp32, tmp:tmp -> tmp33, tmp:tmp -> tmp34, tmp:tmp -> tmp35, tmp:tmp -> tmp36, tmp:tmp -> tmp37, tmp:tmp -> tmp38, tmp:tmp -> tmp39, tmp:tmp -> tmp40, class:Term -> Term1, tmp:tmp -> tmp41, tmp:tmp -> tmp42, tmp:tmp -> tmp43, tmp:block$res -> block$res26, class:Var -> Var, tmp:block$res -> block$res27, env -> env, term -> term, tmp:block$res -> block$res23, member:instance$Ident(Gen) -> instance$Ident$_Gen$_, tmp:tmp -> tmp44, class:IntLit -> IntLit, tmp:tmp -> tmp45, tmp:inlinedVal -> inlinedVal4, tmp:block$res -> block$res28, class:BoolLit -> BoolLit, env -> env1)
+//│     defaultImportBindings = HashMap(/storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Iter.mjs -> Iter, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Option.mjs -> Option, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Runtime.mjs -> Runtime, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Predef.mjs -> Predef)
+//│ ═══[COMPILATION ERROR] No definition found in scope for member 'infer$tailrec'
+//│ FAILURE: Unexpected runtime error
+//│ FAILURE LOCATION: mkQuery (JSBackendDiffMaker.scala:259)
+//│ ═══[RUNTIME ERROR] ReferenceError: infer$tailrec is not defined
+//│     at REPL109:1:234
+//│     at ContextifyScript.runInThisContext (node:vm:138:12)
+//│     at defaultEval (node:repl:608:24)
+//│     at REPLEvalInContext (node:repl:691:9)
+//│     at AsyncLocalStorage.run (node:internal/async_local_storage/async_context_frame:66:14)
+//│     at REPLServer.REPLEval [as eval] (node:repl:690:19)
+//│     at REPLServer.onLine (node:repl:828:12)
+//│     at REPLServer.emit (node:events:514:20)
+//│     at [_onLine] [as _onLine] (node:internal/readline/interface:474:12)
+//│     at [_normalWrite] [as _normalWrite] (node:internal/readline/interface:669:18)
+//│ FAILURE: Unexpected runtime error
+//│ FAILURE LOCATION: processIRBlock (JSBackendDiffMaker.scala:299)
+//│ ═══[RUNTIME ERROR] Expected: '"Bool"', got: 'undefined'
 
 :expect "Int"
 emptyEnv |- App(id, IntLit(5))
-//│ = "Int"
+//│ FAILURE: Unexpected compilation error
+//│ FAILURE LOCATION: lookup_! (Scope.scala:136)
+//│ FAILURE INFO: Tuple2:
+//│   _1 = Tuple2:
+//│     _1 = member:infer$tailrec⁰
+//│     _2 = class hkmc2.semantics.BlockMemberSymbol
+//│   _2 = Scope:
+//│     parentOrCfg = Left of Cfg:
+//│       escapeChars = true
+//│       useSuperscripts = false
+//│       includeZero = false
+//│       defaultName = "tmp"
+//│     curThis = S of S of globalThis:globalThis⁰
+//│     bindings = HashMap(term -> term1, member:instance$Ident(Gen) -> instance$Ident$_Gen$_1, tmp:runtime -> runtime, tmp:block$res -> block$res12, tmp:tmp -> tmp46, tmp:definitionMetadata -> definitionMetadata, tmp:tmp -> tmp47, tmp:prettyPrint -> prettyPrint, tmp:inlinedVal -> inlinedVal5, tmp:Term -> Term, tmp:Block -> Block, tmp:tmp -> tmp1, tmp:block$res -> block$res29, tmp:option -> option, tmp:block$res -> block$res13, env -> env2, term -> term2, t1 -> t1, t2 -> t2, member:instance$Ident(Gen) -> instance$Ident$_Gen$_2, tmp:inlinedVal -> inlinedVal, tmp:tmp -> tmp48, tmp:tmp -> tmp49, tmp:tmp -> tmp2, tmp:inlinedVal -> inlinedVal6, tmp:scrut -> scrut, tmp:block$res -> block$res14, tmp:block$res -> block$res30, env -> env3, term -> term3, tmp:tmp -> tmp3, tmp:tmp -> tmp4, tmp:block$res -> block$res15, member:instance$Ident(Gen) -> instance$Ident$_Gen$_3, tmp:tmp -> tmp50, tmp:tmp -> tmp51, tmp:inlinedVal -> inlinedVal7, tmp:tmp -> tmp5, tmp:block$res -> block$res31, t2 -> t21, tmp:inlinedVal -> inlinedVal1, member:lambda$ -> lambda$, tmp:tmp -> tmp52, env -> env4, tmp:block$res -> block$res, tmp:tmp -> tmp6, tmp:scrut -> scrut1, tmp:block$res -> block$res1, tmp:block$res -> block$res16, member:instance$Ident(Gen) -> instance$Ident$_Gen$_4, tmp:block$res -> block$res2, tmp:tmp -> tmp53, tmp:tmp -> tmp54, tmp:inlinedVal -> inlinedVal8, member:Option -> Option, tmp:block$res -> block$res32, member:Type -> Type1, member:TVar -> TVar1, member:TFun -> TFun1, tmp:tmp -> tmp7, tmp:tmp -> tmp55, member:TPrim -> TPrim1, tmp:tmp -> tmp8, env -> env5, class:Type -> Type, tmp:tmp -> tmp9, tmp:tmp -> tmp10, tmp:tmp -> tmp11, tmp:tmp -> tmp12, member:instance$Ident(Gen) -> instance$Ident$_Gen$_5, class:TFun -> TFun, tmp:tmp -> tmp13, tmp:tmp -> tmp56, tmp:block$res -> block$res17, tmp:tmp -> tmp57, tmp:inlinedVal -> inlinedVal9, tmp:block$res -> block$res33, tmp:tmp -> tmp58, tmp:tmp -> tmp59, tmp:tmp -> tmp14, env -> env6, tmp:tmp -> tmp15, tmp:tmp -> tmp16, tmp:tmp -> tmp17, tmp:tmp -> tmp18, member:instance$Ident(Gen) -> instance$Ident$_Gen$_6, tmp:tmp -> tmp19, tmp:tmp -> tmp60, tmp:tmp -> tmp61, tmp:inlinedVal -> inlinedVal10, tmp:inlinedVal -> inlinedVal2, tmp:block$res -> block$res34, tmp:tmp -> tmp20, tmp:scrut -> scrut2, tmp:block$res -> block$res18, tmp:block$res -> block$res7, emptySub -> emptySub, tmp:tmp -> tmp21, tmp:tmp -> tmp22, tmp:tmp -> tmp23, tmp:tmp -> tmp, tmp:tmp -> tmp24, member:Predef -> Predef, tmp:block$res -> block$res8, tmp:block$res -> block$res19, member:applyPattern -> applyPattern, tmp:tmp -> tmp25, tmp:tmp -> tmp26, tmp:tmp -> tmp27, tmp:inlinedVal -> inlinedVal3, tmp:block$res -> block$res9, tmp:tmp -> tmp28, tmp:scrut -> scrut3, member:Unify -> Unify1, tmp:block$res -> block$res20, pattern:Unify -> Unify, member:Env -> Env1, class:Env -> Env, member:Iter -> Iter, class:TVar -> TVar, class:TPrim -> TPrim, member:Runtime -> Runtime, member:inferTop -> inferTop, tmp:block$res -> block$res5, member:Scheme -> Scheme1, class:Scheme -> Scheme, tmp:block$res -> block$res24, tmp:block$res -> block$res10, member:unify' -> unify$_, member:inferType -> inferType, tmp:block$res -> block$res3, TInt -> TInt, TBool -> TBool, tmp:block$res -> block$res4, member:Term -> Term2, member:IntLit -> IntLit1, member:Var -> Var1, member:App -> App1, tmp:block$res -> block$res11, member:Abs -> Abs1, member:BoolLit -> BoolLit1, member:unify -> unify, member:ShowTerm -> ShowTerm1, pattern:ShowTerm -> ShowTerm, class:Abs -> Abs, tmp:block$res -> block$res25, id -> id, const -> const1, class:App -> App, tmp:block$res -> block$res21, emptyEnv -> emptyEnv, apply -> apply, tmp:block$res -> block$res6, tmp:tmp -> tmp29, tmp:block$res -> block$res22, compose -> compose, member:Subst -> Subst1, class:Subst -> Subst, member:Gen -> Gen1, class:Gen -> Gen, tmp:tmp -> tmp30, tmp:tmp -> tmp31, tmp:tmp -> tmp32, tmp:tmp -> tmp33, tmp:tmp -> tmp34, tmp:tmp -> tmp35, tmp:tmp -> tmp36, tmp:tmp -> tmp37, tmp:tmp -> tmp38, tmp:tmp -> tmp39, tmp:tmp -> tmp40, class:Term -> Term1, tmp:tmp -> tmp41, tmp:tmp -> tmp42, tmp:tmp -> tmp43, tmp:block$res -> block$res26, class:Var -> Var, tmp:block$res -> block$res27, env -> env, term -> term, tmp:block$res -> block$res23, member:instance$Ident(Gen) -> instance$Ident$_Gen$_, tmp:tmp -> tmp44, class:IntLit -> IntLit, tmp:tmp -> tmp45, tmp:inlinedVal -> inlinedVal4, tmp:block$res -> block$res28, class:BoolLit -> BoolLit, env -> env1)
+//│     defaultImportBindings = HashMap(/storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Iter.mjs -> Iter, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Option.mjs -> Option, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Runtime.mjs -> Runtime, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Predef.mjs -> Predef)
+//│ ═══[COMPILATION ERROR] No definition found in scope for member 'infer$tailrec'
+//│ FAILURE: Unexpected runtime error
+//│ FAILURE LOCATION: mkQuery (JSBackendDiffMaker.scala:259)
+//│ ═══[RUNTIME ERROR] ReferenceError: infer$tailrec is not defined
+//│     at REPL112:1:283
+//│     at ContextifyScript.runInThisContext (node:vm:138:12)
+//│     at defaultEval (node:repl:608:24)
+//│     at REPLEvalInContext (node:repl:691:9)
+//│     at AsyncLocalStorage.run (node:internal/async_local_storage/async_context_frame:66:14)
+//│     at REPLServer.REPLEval [as eval] (node:repl:690:19)
+//│     at REPLServer.onLine (node:repl:828:12)
+//│     at REPLServer.emit (node:events:514:20)
+//│     at [_onLine] [as _onLine] (node:internal/readline/interface:474:12)
+//│     at [_normalWrite] [as _normalWrite] (node:internal/readline/interface:669:18)
+//│ FAILURE: Unexpected runtime error
+//│ FAILURE LOCATION: processIRBlock (JSBackendDiffMaker.scala:299)
+//│ ═══[RUNTIME ERROR] Expected: '"Int"', got: 'undefined'
 
 :expect "Int"
 emptyEnv |-  App(id, App(id, IntLit(5)))
-//│ = "Int"
+//│ FAILURE: Unexpected compilation error
+//│ FAILURE LOCATION: lookup_! (Scope.scala:136)
+//│ FAILURE INFO: Tuple2:
+//│   _1 = Tuple2:
+//│     _1 = member:infer$tailrec⁰
+//│     _2 = class hkmc2.semantics.BlockMemberSymbol
+//│   _2 = Scope:
+//│     parentOrCfg = Left of Cfg:
+//│       escapeChars = true
+//│       useSuperscripts = false
+//│       includeZero = false
+//│       defaultName = "tmp"
+//│     curThis = S of S of globalThis:globalThis⁰
+//│     bindings = HashMap(term -> term1, member:instance$Ident(Gen) -> instance$Ident$_Gen$_1, tmp:runtime -> runtime, tmp:block$res -> block$res12, tmp:tmp -> tmp46, tmp:definitionMetadata -> definitionMetadata, tmp:tmp -> tmp47, tmp:prettyPrint -> prettyPrint, tmp:inlinedVal -> inlinedVal5, tmp:Term -> Term, tmp:Block -> Block, tmp:tmp -> tmp1, tmp:block$res -> block$res29, tmp:option -> option, tmp:block$res -> block$res13, env -> env2, term -> term2, t1 -> t1, t2 -> t2, member:instance$Ident(Gen) -> instance$Ident$_Gen$_2, tmp:inlinedVal -> inlinedVal, tmp:tmp -> tmp48, tmp:tmp -> tmp49, tmp:tmp -> tmp2, tmp:inlinedVal -> inlinedVal6, tmp:scrut -> scrut, tmp:block$res -> block$res14, tmp:block$res -> block$res30, env -> env3, term -> term3, tmp:tmp -> tmp3, tmp:tmp -> tmp4, tmp:block$res -> block$res15, member:instance$Ident(Gen) -> instance$Ident$_Gen$_3, tmp:tmp -> tmp50, tmp:tmp -> tmp51, tmp:inlinedVal -> inlinedVal7, tmp:tmp -> tmp5, tmp:block$res -> block$res31, t2 -> t21, tmp:inlinedVal -> inlinedVal1, tmp:tmp -> tmp52, env -> env4, tmp:block$res -> block$res, tmp:tmp -> tmp6, tmp:scrut -> scrut1, tmp:block$res -> block$res1, tmp:block$res -> block$res16, member:instance$Ident(Gen) -> instance$Ident$_Gen$_4, tmp:block$res -> block$res2, tmp:tmp -> tmp53, tmp:tmp -> tmp54, tmp:inlinedVal -> inlinedVal8, member:Option -> Option, tmp:block$res -> block$res32, member:Type -> Type1, member:TVar -> TVar1, member:TFun -> TFun1, tmp:tmp -> tmp7, tmp:tmp -> tmp55, member:TPrim -> TPrim1, tmp:tmp -> tmp8, env -> env5, class:Type -> Type, tmp:tmp -> tmp9, tmp:tmp -> tmp10, tmp:tmp -> tmp11, tmp:tmp -> tmp12, member:instance$Ident(Gen) -> instance$Ident$_Gen$_5, class:TFun -> TFun, tmp:tmp -> tmp13, tmp:tmp -> tmp56, tmp:block$res -> block$res17, tmp:tmp -> tmp57, tmp:inlinedVal -> inlinedVal9, tmp:block$res -> block$res33, tmp:tmp -> tmp58, tmp:tmp -> tmp59, tmp:tmp -> tmp14, env -> env6, tmp:tmp -> tmp15, tmp:tmp -> tmp16, tmp:tmp -> tmp17, tmp:tmp -> tmp18, member:instance$Ident(Gen) -> instance$Ident$_Gen$_6, tmp:tmp -> tmp19, tmp:tmp -> tmp60, tmp:tmp -> tmp61, tmp:inlinedVal -> inlinedVal10, tmp:inlinedVal -> inlinedVal2, tmp:block$res -> block$res34, tmp:tmp -> tmp20, tmp:scrut -> scrut2, tmp:block$res -> block$res18, tmp:tmp -> tmp62, tmp:tmp -> tmp63, tmp:tmp -> tmp64, tmp:block$res -> block$res7, env -> env7, emptySub -> emptySub, tmp:tmp -> tmp21, tmp:tmp -> tmp22, tmp:tmp -> tmp23, member:instance$Ident(Gen) -> instance$Ident$_Gen$_7, tmp:tmp -> tmp, tmp:tmp -> tmp24, tmp:tmp -> tmp65, member:Predef -> Predef, tmp:block$res -> block$res8, tmp:block$res -> block$res19, tmp:tmp -> tmp66, tmp:inlinedVal -> inlinedVal11, member:applyPattern -> applyPattern, tmp:block$res -> block$res35, tmp:tmp -> tmp25, tmp:tmp -> tmp26, tmp:tmp -> tmp27, tmp:inlinedVal -> inlinedVal3, tmp:block$res -> block$res9, tmp:tmp -> tmp28, tmp:scrut -> scrut3, member:Unify -> Unify1, tmp:block$res -> block$res20, pattern:Unify -> Unify, member:Env -> Env1, class:Env -> Env, member:Iter -> Iter, class:TVar -> TVar, class:TPrim -> TPrim, member:Runtime -> Runtime, tmp:block$res -> block$res3, TInt -> TInt, TBool -> TBool, tmp:block$res -> block$res4, member:Term -> Term2, member:IntLit -> IntLit1, member:Var -> Var1, member:App -> App1, member:Abs -> Abs1, member:BoolLit -> BoolLit1, member:ShowTerm -> ShowTerm1, pattern:ShowTerm -> ShowTerm, class:Abs -> Abs, class:App -> App, tmp:block$res -> block$res21, emptyEnv -> emptyEnv, tmp:tmp -> tmp29, tmp:block$res -> block$res22, member:Gen -> Gen1, class:Gen -> Gen, class:Term -> Term1, class:Var -> Var, tmp:block$res -> block$res23, class:IntLit -> IntLit, class:BoolLit -> BoolLit, member:lambda$ -> lambda$, member:inferTop -> inferTop, tmp:block$res -> block$res5, member:Scheme -> Scheme1, class:Scheme -> Scheme, tmp:block$res -> block$res24, tmp:block$res -> block$res10, member:unify' -> unify$_, member:inferType -> inferType, tmp:block$res -> block$res11, member:unify -> unify, tmp:block$res -> block$res25, id -> id, const -> const1, apply -> apply, tmp:block$res -> block$res6, compose -> compose, member:Subst -> Subst1, class:Subst -> Subst, tmp:tmp -> tmp30, tmp:tmp -> tmp31, tmp:tmp -> tmp32, tmp:tmp -> tmp33, tmp:tmp -> tmp34, tmp:tmp -> tmp35, tmp:tmp -> tmp36, tmp:tmp -> tmp37, tmp:tmp -> tmp38, tmp:tmp -> tmp39, tmp:tmp -> tmp40, tmp:tmp -> tmp41, tmp:tmp -> tmp42, tmp:tmp -> tmp43, tmp:block$res -> block$res26, tmp:block$res -> block$res27, env -> env, term -> term, member:instance$Ident(Gen) -> instance$Ident$_Gen$_, tmp:tmp -> tmp44, tmp:tmp -> tmp45, tmp:inlinedVal -> inlinedVal4, tmp:block$res -> block$res28, env -> env1)
+//│     defaultImportBindings = HashMap(/storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Iter.mjs -> Iter, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Option.mjs -> Option, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Runtime.mjs -> Runtime, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Predef.mjs -> Predef)
+//│ ═══[COMPILATION ERROR] No definition found in scope for member 'infer$tailrec'
+//│ FAILURE: Unexpected runtime error
+//│ FAILURE LOCATION: mkQuery (JSBackendDiffMaker.scala:259)
+//│ ═══[RUNTIME ERROR] ReferenceError: infer$tailrec is not defined
+//│     at REPL115:1:334
+//│     at ContextifyScript.runInThisContext (node:vm:138:12)
+//│     at defaultEval (node:repl:608:24)
+//│     at REPLEvalInContext (node:repl:691:9)
+//│     at AsyncLocalStorage.run (node:internal/async_local_storage/async_context_frame:66:14)
+//│     at REPLServer.REPLEval [as eval] (node:repl:690:19)
+//│     at REPLServer.onLine (node:repl:828:12)
+//│     at REPLServer.emit (node:events:514:20)
+//│     at [_onLine] [as _onLine] (node:internal/readline/interface:474:12)
+//│     at [_normalWrite] [as _normalWrite] (node:internal/readline/interface:669:18)
+//│ FAILURE: Unexpected runtime error
+//│ FAILURE LOCATION: processIRBlock (JSBackendDiffMaker.scala:299)
+//│ ═══[RUNTIME ERROR] Expected: '"Int"', got: 'undefined'
 
 :silent
 let env1 = emptyEnv.extend of
@@ -304,11 +601,73 @@ let env1 = emptyEnv.extend of
 
 :expect "Int"
 env1 |- App(Var("id"), IntLit(5))
-//│ = "Int"
+//│ FAILURE: Unexpected compilation error
+//│ FAILURE LOCATION: lookup_! (Scope.scala:136)
+//│ FAILURE INFO: Tuple2:
+//│   _1 = Tuple2:
+//│     _1 = member:infer$tailrec⁰
+//│     _2 = class hkmc2.semantics.BlockMemberSymbol
+//│   _2 = Scope:
+//│     parentOrCfg = Left of Cfg:
+//│       escapeChars = true
+//│       useSuperscripts = false
+//│       includeZero = false
+//│       defaultName = "tmp"
+//│     curThis = S of S of globalThis:globalThis⁰
+//│     bindings = HashMap(term -> term1, member:instance$Ident(Gen) -> instance$Ident$_Gen$_1, tmp:runtime -> runtime, tmp:block$res -> block$res12, tmp:tmp -> tmp46, tmp:definitionMetadata -> definitionMetadata, tmp:tmp -> tmp47, tmp:prettyPrint -> prettyPrint, tmp:inlinedVal -> inlinedVal5, tmp:Term -> Term, tmp:Block -> Block, tmp:tmp -> tmp1, tmp:block$res -> block$res29, tmp:option -> option, tmp:block$res -> block$res13, env -> env2, term -> term2, t1 -> t1, t2 -> t2, member:instance$Ident(Gen) -> instance$Ident$_Gen$_2, tmp:inlinedVal -> inlinedVal, tmp:tmp -> tmp48, tmp:tmp -> tmp49, tmp:tmp -> tmp2, tmp:inlinedVal -> inlinedVal6, tmp:scrut -> scrut, tmp:block$res -> block$res14, tmp:block$res -> block$res30, env -> env3, term -> term3, tmp:tmp -> tmp3, tmp:tmp -> tmp4, tmp:block$res -> block$res15, member:instance$Ident(Gen) -> instance$Ident$_Gen$_3, tmp:tmp -> tmp50, tmp:tmp -> tmp51, tmp:inlinedVal -> inlinedVal7, tmp:tmp -> tmp5, tmp:block$res -> block$res31, t2 -> t21, tmp:inlinedVal -> inlinedVal1, tmp:tmp -> tmp52, env -> env4, tmp:block$res -> block$res, tmp:tmp -> tmp6, tmp:scrut -> scrut1, tmp:block$res -> block$res1, tmp:block$res -> block$res16, member:instance$Ident(Gen) -> instance$Ident$_Gen$_4, tmp:block$res -> block$res2, tmp:tmp -> tmp53, tmp:tmp -> tmp54, tmp:inlinedVal -> inlinedVal8, member:Option -> Option, tmp:block$res -> block$res32, member:Type -> Type1, member:TVar -> TVar1, member:TFun -> TFun1, tmp:tmp -> tmp7, tmp:tmp -> tmp55, member:TPrim -> TPrim1, tmp:tmp -> tmp8, env -> env5, class:Type -> Type, tmp:tmp -> tmp9, tmp:tmp -> tmp10, tmp:tmp -> tmp11, tmp:tmp -> tmp12, member:instance$Ident(Gen) -> instance$Ident$_Gen$_5, class:TFun -> TFun, tmp:tmp -> tmp13, tmp:tmp -> tmp56, tmp:block$res -> block$res17, tmp:tmp -> tmp57, tmp:inlinedVal -> inlinedVal9, tmp:block$res -> block$res33, tmp:tmp -> tmp58, tmp:tmp -> tmp59, tmp:tmp -> tmp14, env -> env6, tmp:tmp -> tmp15, tmp:tmp -> tmp16, tmp:tmp -> tmp17, tmp:tmp -> tmp18, member:instance$Ident(Gen) -> instance$Ident$_Gen$_6, tmp:tmp -> tmp19, tmp:tmp -> tmp60, tmp:tmp -> tmp61, tmp:inlinedVal -> inlinedVal10, tmp:inlinedVal -> inlinedVal2, tmp:block$res -> block$res34, tmp:tmp -> tmp20, tmp:scrut -> scrut2, tmp:block$res -> block$res18, tmp:tmp -> tmp62, tmp:tmp -> tmp63, tmp:tmp -> tmp64, tmp:block$res -> block$res7, env -> env7, emptySub -> emptySub, tmp:tmp -> tmp21, tmp:tmp -> tmp22, tmp:tmp -> tmp23, member:instance$Ident(Gen) -> instance$Ident$_Gen$_7, tmp:tmp -> tmp, tmp:tmp -> tmp24, tmp:tmp -> tmp65, member:Predef -> Predef, tmp:block$res -> block$res8, tmp:block$res -> block$res19, tmp:tmp -> tmp66, tmp:inlinedVal -> inlinedVal11, member:applyPattern -> applyPattern, tmp:block$res -> block$res35, env1 -> env11, tmp:tmp -> tmp25, tmp:tmp -> tmp26, tmp:tmp -> tmp27, tmp:inlinedVal -> inlinedVal3, tmp:tmp -> tmp67, tmp:tmp -> tmp68, tmp:block$res -> block$res9, tmp:tmp -> tmp28, tmp:tmp -> tmp69, tmp:scrut -> scrut3, tmp:tmp -> tmp70, member:Unify -> Unify1, tmp:block$res -> block$res20, tmp:tmp -> tmp71, pattern:Unify -> Unify, tmp:tmp -> tmp72, tmp:block$res -> block$res36, member:Env -> Env1, class:Env -> Env, tmp:tmp -> tmp73, tmp:tmp -> tmp74, member:Iter -> Iter, tmp:tmp -> tmp75, class:TVar -> TVar, env -> env8, member:instance$Ident(Gen) -> instance$Ident$_Gen$_8, tmp:tmp -> tmp76, tmp:tmp -> tmp77, tmp:inlinedVal -> inlinedVal12, tmp:block$res -> block$res37, class:TPrim -> TPrim, member:Runtime -> Runtime, tmp:block$res -> block$res3, TInt -> TInt, TBool -> TBool, tmp:block$res -> block$res4, member:Term -> Term2, member:IntLit -> IntLit1, member:Var -> Var1, member:App -> App1, member:Abs -> Abs1, member:BoolLit -> BoolLit1, member:ShowTerm -> ShowTerm1, pattern:ShowTerm -> ShowTerm, class:Abs -> Abs, class:App -> App, tmp:block$res -> block$res21, emptyEnv -> emptyEnv, tmp:tmp -> tmp29, tmp:block$res -> block$res22, member:Gen -> Gen1, class:Gen -> Gen, class:Term -> Term1, class:Var -> Var, tmp:block$res -> block$res23, class:IntLit -> IntLit, class:BoolLit -> BoolLit, member:lambda$ -> lambda$, member:inferTop -> inferTop, tmp:block$res -> block$res5, member:Scheme -> Scheme1, class:Scheme -> Scheme, tmp:block$res -> block$res24, tmp:block$res -> block$res10, member:unify' -> unify$_, member:inferType -> inferType, tmp:block$res -> block$res11, member:unify -> unify, tmp:block$res -> block$res25, id -> id, const -> const1, apply -> apply, tmp:block$res -> block$res6, compose -> compose, member:Subst -> Subst1, class:Subst -> Subst, tmp:tmp -> tmp30, tmp:tmp -> tmp31, tmp:tmp -> tmp32, tmp:tmp -> tmp33, tmp:tmp -> tmp34, tmp:tmp -> tmp35, tmp:tmp -> tmp36, tmp:tmp -> tmp37, tmp:tmp -> tmp38, tmp:tmp -> tmp39, tmp:tmp -> tmp40, tmp:tmp -> tmp41, tmp:tmp -> tmp42, tmp:tmp -> tmp43, tmp:block$res -> block$res26, tmp:block$res -> block$res27, env -> env, term -> term, member:instance$Ident(Gen) -> instance$Ident$_Gen$_, tmp:tmp -> tmp44, tmp:tmp -> tmp45, tmp:inlinedVal -> inlinedVal4, tmp:block$res -> block$res28, env -> env1)
+//│     defaultImportBindings = HashMap(/storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Iter.mjs -> Iter, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Option.mjs -> Option, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Runtime.mjs -> Runtime, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Predef.mjs -> Predef)
+//│ ═══[COMPILATION ERROR] No definition found in scope for member 'infer$tailrec'
+//│ FAILURE: Unexpected runtime error
+//│ FAILURE LOCATION: mkQuery (JSBackendDiffMaker.scala:259)
+//│ ═══[RUNTIME ERROR] ReferenceError: infer$tailrec is not defined
+//│     at REPL120:1:329
+//│     at ContextifyScript.runInThisContext (node:vm:138:12)
+//│     at defaultEval (node:repl:608:24)
+//│     at REPLEvalInContext (node:repl:691:9)
+//│     at AsyncLocalStorage.run (node:internal/async_local_storage/async_context_frame:66:14)
+//│     at REPLServer.REPLEval [as eval] (node:repl:690:19)
+//│     at REPLServer.onLine (node:repl:828:12)
+//│     at REPLServer.emit (node:events:514:20)
+//│     at [_onLine] [as _onLine] (node:internal/readline/interface:474:12)
+//│     at [_normalWrite] [as _normalWrite] (node:internal/readline/interface:669:18)
+//│ FAILURE: Unexpected runtime error
+//│ FAILURE LOCATION: processIRBlock (JSBackendDiffMaker.scala:299)
+//│ ═══[RUNTIME ERROR] Expected: '"Int"', got: 'undefined'
 
 :expect "Bool"
 env1 |- App(Var("id"), BoolLit(true))
-//│ = "Bool"
+//│ FAILURE: Unexpected compilation error
+//│ FAILURE LOCATION: lookup_! (Scope.scala:136)
+//│ FAILURE INFO: Tuple2:
+//│   _1 = Tuple2:
+//│     _1 = member:infer$tailrec⁰
+//│     _2 = class hkmc2.semantics.BlockMemberSymbol
+//│   _2 = Scope:
+//│     parentOrCfg = Left of Cfg:
+//│       escapeChars = true
+//│       useSuperscripts = false
+//│       includeZero = false
+//│       defaultName = "tmp"
+//│     curThis = S of S of globalThis:globalThis⁰
+//│     bindings = HashMap(term -> term1, member:instance$Ident(Gen) -> instance$Ident$_Gen$_1, tmp:runtime -> runtime, tmp:block$res -> block$res12, tmp:tmp -> tmp46, tmp:definitionMetadata -> definitionMetadata, tmp:tmp -> tmp47, tmp:prettyPrint -> prettyPrint, tmp:inlinedVal -> inlinedVal5, tmp:Term -> Term, tmp:Block -> Block, tmp:tmp -> tmp1, tmp:block$res -> block$res29, tmp:option -> option, tmp:block$res -> block$res13, env -> env2, term -> term2, t1 -> t1, t2 -> t2, member:instance$Ident(Gen) -> instance$Ident$_Gen$_2, tmp:inlinedVal -> inlinedVal, tmp:tmp -> tmp48, tmp:tmp -> tmp49, tmp:tmp -> tmp2, tmp:inlinedVal -> inlinedVal6, tmp:scrut -> scrut, tmp:block$res -> block$res14, tmp:block$res -> block$res30, env -> env3, term -> term3, tmp:tmp -> tmp3, tmp:tmp -> tmp4, tmp:block$res -> block$res15, member:instance$Ident(Gen) -> instance$Ident$_Gen$_3, tmp:tmp -> tmp50, tmp:tmp -> tmp51, tmp:inlinedVal -> inlinedVal7, tmp:tmp -> tmp5, tmp:block$res -> block$res31, t2 -> t21, tmp:inlinedVal -> inlinedVal1, tmp:tmp -> tmp52, env -> env4, tmp:block$res -> block$res, tmp:tmp -> tmp6, tmp:scrut -> scrut1, tmp:block$res -> block$res1, tmp:block$res -> block$res16, member:instance$Ident(Gen) -> instance$Ident$_Gen$_4, tmp:block$res -> block$res2, tmp:tmp -> tmp53, tmp:tmp -> tmp54, tmp:inlinedVal -> inlinedVal8, member:Option -> Option, tmp:block$res -> block$res32, member:Type -> Type1, member:TVar -> TVar1, member:TFun -> TFun1, tmp:tmp -> tmp7, tmp:tmp -> tmp55, member:TPrim -> TPrim1, tmp:tmp -> tmp8, env -> env5, class:Type -> Type, tmp:tmp -> tmp9, tmp:tmp -> tmp10, tmp:tmp -> tmp11, tmp:tmp -> tmp12, member:instance$Ident(Gen) -> instance$Ident$_Gen$_5, class:TFun -> TFun, tmp:tmp -> tmp13, tmp:tmp -> tmp56, tmp:block$res -> block$res17, tmp:tmp -> tmp57, tmp:inlinedVal -> inlinedVal9, tmp:block$res -> block$res33, tmp:tmp -> tmp58, tmp:tmp -> tmp59, tmp:tmp -> tmp14, env -> env6, tmp:tmp -> tmp15, tmp:tmp -> tmp16, tmp:tmp -> tmp17, tmp:tmp -> tmp18, member:instance$Ident(Gen) -> instance$Ident$_Gen$_6, tmp:tmp -> tmp19, tmp:tmp -> tmp60, tmp:tmp -> tmp61, tmp:inlinedVal -> inlinedVal10, tmp:inlinedVal -> inlinedVal2, tmp:block$res -> block$res34, tmp:tmp -> tmp20, tmp:scrut -> scrut2, tmp:block$res -> block$res18, tmp:tmp -> tmp62, tmp:tmp -> tmp63, tmp:tmp -> tmp64, tmp:block$res -> block$res7, env -> env7, emptySub -> emptySub, tmp:tmp -> tmp21, tmp:tmp -> tmp22, tmp:tmp -> tmp23, member:instance$Ident(Gen) -> instance$Ident$_Gen$_7, tmp:tmp -> tmp, tmp:tmp -> tmp24, tmp:tmp -> tmp65, member:Predef -> Predef, tmp:block$res -> block$res8, tmp:block$res -> block$res19, tmp:tmp -> tmp66, tmp:inlinedVal -> inlinedVal11, member:applyPattern -> applyPattern, tmp:block$res -> block$res35, env1 -> env11, tmp:tmp -> tmp25, tmp:tmp -> tmp26, tmp:tmp -> tmp27, tmp:inlinedVal -> inlinedVal3, tmp:tmp -> tmp67, tmp:tmp -> tmp68, tmp:block$res -> block$res9, tmp:tmp -> tmp28, tmp:tmp -> tmp69, tmp:scrut -> scrut3, tmp:tmp -> tmp70, member:Unify -> Unify1, tmp:block$res -> block$res20, tmp:tmp -> tmp71, pattern:Unify -> Unify, tmp:tmp -> tmp72, tmp:block$res -> block$res36, member:Env -> Env1, class:Env -> Env, tmp:tmp -> tmp73, tmp:tmp -> tmp74, member:Iter -> Iter, tmp:tmp -> tmp75, class:TVar -> TVar, env -> env8, member:instance$Ident(Gen) -> instance$Ident$_Gen$_8, tmp:tmp -> tmp76, tmp:tmp -> tmp77, tmp:inlinedVal -> inlinedVal12, tmp:block$res -> block$res37, class:TPrim -> TPrim, tmp:tmp -> tmp78, member:Runtime -> Runtime, tmp:tmp -> tmp79, tmp:tmp -> tmp80, env -> env9, member:instance$Ident(Gen) -> instance$Ident$_Gen$_9, tmp:tmp -> tmp81, tmp:tmp -> tmp82, tmp:inlinedVal -> inlinedVal13, tmp:block$res -> block$res38, tmp:block$res -> block$res3, TInt -> TInt, TBool -> TBool, tmp:block$res -> block$res4, member:Term -> Term2, member:IntLit -> IntLit1, member:Var -> Var1, member:App -> App1, member:Abs -> Abs1, member:BoolLit -> BoolLit1, member:ShowTerm -> ShowTerm1, pattern:ShowTerm -> ShowTerm, class:Abs -> Abs, class:App -> App, tmp:block$res -> block$res21, emptyEnv -> emptyEnv, tmp:tmp -> tmp29, tmp:block$res -> block$res22, member:Gen -> Gen1, class:Gen -> Gen, class:Term -> Term1, class:Var -> Var, tmp:block$res -> block$res23, class:IntLit -> IntLit, class:BoolLit -> BoolLit, member:lambda$ -> lambda$, member:inferTop -> inferTop, tmp:block$res -> block$res5, member:Scheme -> Scheme1, class:Scheme -> Scheme, tmp:block$res -> block$res24, tmp:block$res -> block$res10, member:unify' -> unify$_, member:inferType -> inferType, tmp:block$res -> block$res11, member:unify -> unify, tmp:block$res -> block$res25, id -> id, const -> const1, apply -> apply, tmp:block$res -> block$res6, compose -> compose, member:Subst -> Subst1, class:Subst -> Subst, tmp:tmp -> tmp30, tmp:tmp -> tmp31, tmp:tmp -> tmp32, tmp:tmp -> tmp33, tmp:tmp -> tmp34, tmp:tmp -> tmp35, tmp:tmp -> tmp36, tmp:tmp -> tmp37, tmp:tmp -> tmp38, tmp:tmp -> tmp39, tmp:tmp -> tmp40, tmp:tmp -> tmp41, tmp:tmp -> tmp42, tmp:tmp -> tmp43, tmp:block$res -> block$res26, tmp:block$res -> block$res27, env -> env, term -> term, member:instance$Ident(Gen) -> instance$Ident$_Gen$_, tmp:tmp -> tmp44, tmp:tmp -> tmp45, tmp:inlinedVal -> inlinedVal4, tmp:block$res -> block$res28, env -> env1)
+//│     defaultImportBindings = HashMap(/storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Iter.mjs -> Iter, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Option.mjs -> Option, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Runtime.mjs -> Runtime, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Predef.mjs -> Predef)
+//│ ═══[COMPILATION ERROR] No definition found in scope for member 'infer$tailrec'
+//│ FAILURE: Unexpected runtime error
+//│ FAILURE LOCATION: mkQuery (JSBackendDiffMaker.scala:259)
+//│ ═══[RUNTIME ERROR] ReferenceError: infer$tailrec is not defined
+//│     at REPL123:1:333
+//│     at ContextifyScript.runInThisContext (node:vm:138:12)
+//│     at defaultEval (node:repl:608:24)
+//│     at REPLEvalInContext (node:repl:691:9)
+//│     at AsyncLocalStorage.run (node:internal/async_local_storage/async_context_frame:66:14)
+//│     at REPLServer.REPLEval [as eval] (node:repl:690:19)
+//│     at REPLServer.onLine (node:repl:828:12)
+//│     at REPLServer.emit (node:events:514:20)
+//│     at [_onLine] [as _onLine] (node:internal/readline/interface:474:12)
+//│     at [_normalWrite] [as _normalWrite] (node:internal/readline/interface:669:18)
+//│ FAILURE: Unexpected runtime error
+//│ FAILURE LOCATION: processIRBlock (JSBackendDiffMaker.scala:299)
+//│ ═══[RUNTIME ERROR] Expected: '"Bool"', got: 'undefined'
 
 :silent
 let env2 = env1.extend of
@@ -316,11 +675,55 @@ let env2 = env1.extend of
   Scheme(new Set(), TFun(TInt, TFun(TInt, TInt)))
 
 env2 |- App(App(Var("add"), IntLit(5)), IntLit(5))
-//│ = "Int"
+//│ FAILURE: Unexpected compilation error
+//│ FAILURE LOCATION: lookup_! (Scope.scala:136)
+//│ FAILURE INFO: Tuple2:
+//│   _1 = Tuple2:
+//│     _1 = member:infer$tailrec⁰
+//│     _2 = class hkmc2.semantics.BlockMemberSymbol
+//│   _2 = Scope:
+//│     parentOrCfg = Left of Cfg:
+//│       escapeChars = true
+//│       useSuperscripts = false
+//│       includeZero = false
+//│       defaultName = "tmp"
+//│     curThis = S of S of globalThis:globalThis⁰
+//│     bindings = HashMap(term -> term1, member:instance$Ident(Gen) -> instance$Ident$_Gen$_1, tmp:runtime -> runtime, tmp:block$res -> block$res12, tmp:tmp -> tmp46, tmp:definitionMetadata -> definitionMetadata, tmp:tmp -> tmp47, tmp:prettyPrint -> prettyPrint, tmp:inlinedVal -> inlinedVal5, tmp:Term -> Term, tmp:Block -> Block, tmp:tmp -> tmp1, tmp:block$res -> block$res29, tmp:option -> option, tmp:block$res -> block$res13, env -> env2, term -> term2, t1 -> t1, t2 -> t2, member:instance$Ident(Gen) -> instance$Ident$_Gen$_2, tmp:inlinedVal -> inlinedVal, tmp:tmp -> tmp48, tmp:tmp -> tmp49, tmp:tmp -> tmp2, tmp:inlinedVal -> inlinedVal6, tmp:scrut -> scrut, tmp:block$res -> block$res14, tmp:block$res -> block$res30, env -> env3, term -> term3, tmp:tmp -> tmp3, tmp:tmp -> tmp4, tmp:block$res -> block$res15, member:instance$Ident(Gen) -> instance$Ident$_Gen$_3, tmp:tmp -> tmp50, tmp:tmp -> tmp51, tmp:inlinedVal -> inlinedVal7, tmp:tmp -> tmp5, tmp:block$res -> block$res31, t2 -> t21, tmp:inlinedVal -> inlinedVal1, tmp:tmp -> tmp52, env -> env4, tmp:block$res -> block$res, tmp:tmp -> tmp6, tmp:scrut -> scrut1, tmp:block$res -> block$res1, tmp:block$res -> block$res16, member:instance$Ident(Gen) -> instance$Ident$_Gen$_4, tmp:block$res -> block$res2, tmp:tmp -> tmp53, tmp:tmp -> tmp54, tmp:inlinedVal -> inlinedVal8, member:Option -> Option, tmp:block$res -> block$res32, member:Type -> Type1, member:TVar -> TVar1, member:TFun -> TFun1, tmp:tmp -> tmp7, tmp:tmp -> tmp55, member:TPrim -> TPrim1, tmp:tmp -> tmp8, env -> env5, class:Type -> Type, tmp:tmp -> tmp9, tmp:tmp -> tmp10, tmp:tmp -> tmp11, tmp:tmp -> tmp12, member:instance$Ident(Gen) -> instance$Ident$_Gen$_5, class:TFun -> TFun, tmp:tmp -> tmp13, tmp:tmp -> tmp56, tmp:block$res -> block$res17, tmp:tmp -> tmp57, tmp:inlinedVal -> inlinedVal9, tmp:block$res -> block$res33, tmp:tmp -> tmp58, tmp:tmp -> tmp59, tmp:tmp -> tmp14, env -> env6, tmp:tmp -> tmp15, tmp:tmp -> tmp16, tmp:tmp -> tmp17, tmp:tmp -> tmp18, member:instance$Ident(Gen) -> instance$Ident$_Gen$_6, tmp:tmp -> tmp19, tmp:tmp -> tmp60, tmp:tmp -> tmp61, tmp:inlinedVal -> inlinedVal10, tmp:inlinedVal -> inlinedVal2, tmp:block$res -> block$res34, tmp:tmp -> tmp20, tmp:scrut -> scrut2, tmp:block$res -> block$res18, tmp:tmp -> tmp62, tmp:tmp -> tmp63, tmp:tmp -> tmp64, tmp:block$res -> block$res7, env -> env7, emptySub -> emptySub, tmp:tmp -> tmp21, tmp:tmp -> tmp22, tmp:tmp -> tmp23, member:instance$Ident(Gen) -> instance$Ident$_Gen$_7, tmp:tmp -> tmp, tmp:tmp -> tmp24, tmp:tmp -> tmp65, member:Predef -> Predef, tmp:block$res -> block$res8, tmp:block$res -> block$res19, tmp:tmp -> tmp66, tmp:inlinedVal -> inlinedVal11, member:applyPattern -> applyPattern, tmp:block$res -> block$res35, env1 -> env11, tmp:tmp -> tmp25, tmp:tmp -> tmp26, tmp:tmp -> tmp27, tmp:inlinedVal -> inlinedVal3, tmp:tmp -> tmp67, tmp:tmp -> tmp68, tmp:block$res -> block$res9, tmp:tmp -> tmp28, tmp:tmp -> tmp69, tmp:scrut -> scrut3, tmp:tmp -> tmp70, member:Unify -> Unify1, tmp:block$res -> block$res20, tmp:tmp -> tmp71, pattern:Unify -> Unify, tmp:tmp -> tmp72, tmp:block$res -> block$res36, member:Env -> Env1, class:Env -> Env, tmp:tmp -> tmp73, tmp:tmp -> tmp74, member:Iter -> Iter, tmp:tmp -> tmp75, class:TVar -> TVar, env -> env8, member:instance$Ident(Gen) -> instance$Ident$_Gen$_8, tmp:tmp -> tmp76, tmp:tmp -> tmp77, tmp:inlinedVal -> inlinedVal12, tmp:block$res -> block$res37, class:TPrim -> TPrim, tmp:tmp -> tmp78, member:Runtime -> Runtime, tmp:tmp -> tmp79, tmp:tmp -> tmp80, env -> env9, member:instance$Ident(Gen) -> instance$Ident$_Gen$_9, tmp:tmp -> tmp81, tmp:tmp -> tmp82, tmp:inlinedVal -> inlinedVal13, tmp:block$res -> block$res38, env2 -> env21, tmp:tmp -> tmp83, tmp:tmp -> tmp84, tmp:tmp -> tmp85, tmp:tmp -> tmp86, tmp:block$res -> block$res39, tmp:block$res -> block$res3, tmp:tmp -> tmp87, TInt -> TInt, tmp:tmp -> tmp88, tmp:tmp -> tmp89, TBool -> TBool, tmp:tmp -> tmp90, tmp:tmp -> tmp91, tmp:block$res -> block$res4, env -> env10, member:Term -> Term2, member:IntLit -> IntLit1, member:instance$Ident(Gen) -> instance$Ident$_Gen$_10, member:Var -> Var1, tmp:tmp -> tmp92, member:App -> App1, tmp:tmp -> tmp93, member:Abs -> Abs1, tmp:inlinedVal -> inlinedVal14, member:BoolLit -> BoolLit1, member:ShowTerm -> ShowTerm1, tmp:block$res -> block$res40, pattern:ShowTerm -> ShowTerm, class:Abs -> Abs, class:App -> App, tmp:block$res -> block$res21, emptyEnv -> emptyEnv, tmp:tmp -> tmp29, tmp:block$res -> block$res22, member:Gen -> Gen1, class:Gen -> Gen, class:Term -> Term1, class:Var -> Var, tmp:block$res -> block$res23, class:IntLit -> IntLit, class:BoolLit -> BoolLit, member:lambda$ -> lambda$, member:inferTop -> inferTop, tmp:block$res -> block$res5, member:Scheme -> Scheme1, class:Scheme -> Scheme, tmp:block$res -> block$res24, tmp:block$res -> block$res10, member:unify' -> unify$_, member:inferType -> inferType, tmp:block$res -> block$res11, member:unify -> unify, tmp:block$res -> block$res25, id -> id, const -> const1, apply -> apply, tmp:block$res -> block$res6, compose -> compose, member:Subst -> Subst1, class:Subst -> Subst, tmp:tmp -> tmp30, tmp:tmp -> tmp31, tmp:tmp -> tmp32, tmp:tmp -> tmp33, tmp:tmp -> tmp34, tmp:tmp -> tmp35, tmp:tmp -> tmp36, tmp:tmp -> tmp37, tmp:tmp -> tmp38, tmp:tmp -> tmp39, tmp:tmp -> tmp40, tmp:tmp -> tmp41, tmp:tmp -> tmp42, tmp:tmp -> tmp43, tmp:block$res -> block$res26, tmp:block$res -> block$res27, env -> env, term -> term, member:instance$Ident(Gen) -> instance$Ident$_Gen$_, tmp:tmp -> tmp44, tmp:tmp -> tmp45, tmp:inlinedVal -> inlinedVal4, tmp:block$res -> block$res28, env -> env1)
+//│     defaultImportBindings = HashMap(/storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Iter.mjs -> Iter, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Option.mjs -> Option, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Runtime.mjs -> Runtime, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Predef.mjs -> Predef)
+//│ ═══[COMPILATION ERROR] No definition found in scope for member 'infer$tailrec'
+//│ FAILURE: Unexpected runtime error
+//│ FAILURE LOCATION: mkQuery (JSBackendDiffMaker.scala:259)
+//│ ═══[RUNTIME ERROR] ReferenceError: infer$tailrec is not defined
+//│     at REPL128:1:434
+//│     at ContextifyScript.runInThisContext (node:vm:138:12)
+//│     at defaultEval (node:repl:608:24)
+//│     at REPLEvalInContext (node:repl:691:9)
+//│     at AsyncLocalStorage.run (node:internal/async_local_storage/async_context_frame:66:14)
+//│     at REPLServer.REPLEval [as eval] (node:repl:690:19)
+//│     at REPLServer.onLine (node:repl:828:12)
+//│     at REPLServer.emit (node:events:514:20)
+//│     at [_onLine] [as _onLine] (node:internal/readline/interface:474:12)
+//│     at [_normalWrite] [as _normalWrite] (node:internal/readline/interface:669:18)
 
 :re
 env2 |- App(App(Var("add"), IntLit(5)), BoolLit(true))
-//│ ═══[RUNTIME ERROR] Error: Cannot unify Int with Bool
+//│ FAILURE: Unexpected compilation error
+//│ FAILURE LOCATION: lookup_! (Scope.scala:136)
+//│ FAILURE INFO: Tuple2:
+//│   _1 = Tuple2:
+//│     _1 = member:infer$tailrec⁰
+//│     _2 = class hkmc2.semantics.BlockMemberSymbol
+//│   _2 = Scope:
+//│     parentOrCfg = Left of Cfg:
+//│       escapeChars = true
+//│       useSuperscripts = false
+//│       includeZero = false
+//│       defaultName = "tmp"
+//│     curThis = S of S of globalThis:globalThis⁰
+//│     bindings = HashMap(term -> term1, member:instance$Ident(Gen) -> instance$Ident$_Gen$_1, tmp:runtime -> runtime, tmp:block$res -> block$res12, tmp:tmp -> tmp46, tmp:definitionMetadata -> definitionMetadata, tmp:tmp -> tmp47, tmp:prettyPrint -> prettyPrint, tmp:inlinedVal -> inlinedVal5, tmp:Term -> Term, tmp:Block -> Block, tmp:tmp -> tmp1, tmp:block$res -> block$res29, tmp:option -> option, tmp:block$res -> block$res13, env -> env2, term -> term2, t1 -> t1, t2 -> t2, member:instance$Ident(Gen) -> instance$Ident$_Gen$_2, tmp:inlinedVal -> inlinedVal, tmp:tmp -> tmp48, tmp:tmp -> tmp49, tmp:tmp -> tmp2, tmp:inlinedVal -> inlinedVal6, tmp:scrut -> scrut, tmp:block$res -> block$res14, tmp:block$res -> block$res30, env -> env3, term -> term3, tmp:tmp -> tmp3, tmp:tmp -> tmp4, tmp:block$res -> block$res15, member:instance$Ident(Gen) -> instance$Ident$_Gen$_3, tmp:tmp -> tmp50, tmp:tmp -> tmp51, tmp:inlinedVal -> inlinedVal7, tmp:tmp -> tmp5, tmp:block$res -> block$res31, t2 -> t21, tmp:inlinedVal -> inlinedVal1, tmp:tmp -> tmp52, env -> env4, tmp:block$res -> block$res, tmp:tmp -> tmp6, tmp:scrut -> scrut1, tmp:block$res -> block$res1, tmp:block$res -> block$res16, member:instance$Ident(Gen) -> instance$Ident$_Gen$_4, tmp:block$res -> block$res2, tmp:tmp -> tmp53, tmp:tmp -> tmp54, tmp:inlinedVal -> inlinedVal8, member:Option -> Option, tmp:block$res -> block$res32, member:Type -> Type1, member:TVar -> TVar1, member:TFun -> TFun1, tmp:tmp -> tmp7, tmp:tmp -> tmp55, member:TPrim -> TPrim1, tmp:tmp -> tmp8, env -> env5, class:Type -> Type, tmp:tmp -> tmp9, tmp:tmp -> tmp10, tmp:tmp -> tmp11, tmp:tmp -> tmp12, member:instance$Ident(Gen) -> instance$Ident$_Gen$_5, class:TFun -> TFun, tmp:tmp -> tmp13, tmp:tmp -> tmp56, tmp:block$res -> block$res17, tmp:tmp -> tmp57, tmp:inlinedVal -> inlinedVal9, tmp:block$res -> block$res33, tmp:tmp -> tmp58, tmp:tmp -> tmp59, tmp:tmp -> tmp14, env -> env6, tmp:tmp -> tmp15, tmp:tmp -> tmp16, tmp:tmp -> tmp17, tmp:tmp -> tmp18, member:instance$Ident(Gen) -> instance$Ident$_Gen$_6, tmp:tmp -> tmp19, tmp:tmp -> tmp60, tmp:tmp -> tmp61, tmp:inlinedVal -> inlinedVal10, tmp:inlinedVal -> inlinedVal2, tmp:block$res -> block$res34, tmp:tmp -> tmp20, tmp:scrut -> scrut2, tmp:block$res -> block$res18, tmp:tmp -> tmp62, tmp:tmp -> tmp63, tmp:tmp -> tmp64, tmp:block$res -> block$res7, env -> env7, emptySub -> emptySub, tmp:tmp -> tmp21, tmp:tmp -> tmp22, tmp:tmp -> tmp23, member:instance$Ident(Gen) -> instance$Ident$_Gen$_7, tmp:tmp -> tmp, tmp:tmp -> tmp24, tmp:tmp -> tmp65, member:Predef -> Predef, tmp:block$res -> block$res8, tmp:block$res -> block$res19, tmp:tmp -> tmp66, tmp:inlinedVal -> inlinedVal11, member:applyPattern -> applyPattern, tmp:block$res -> block$res35, env1 -> env11, tmp:tmp -> tmp25, tmp:tmp -> tmp26, tmp:tmp -> tmp27, tmp:inlinedVal -> inlinedVal3, tmp:tmp -> tmp67, tmp:tmp -> tmp68, tmp:block$res -> block$res9, tmp:tmp -> tmp28, tmp:tmp -> tmp69, tmp:scrut -> scrut3, tmp:tmp -> tmp70, member:Unify -> Unify1, tmp:block$res -> block$res20, tmp:tmp -> tmp71, pattern:Unify -> Unify, tmp:tmp -> tmp72, tmp:block$res -> block$res36, member:Env -> Env1, class:Env -> Env, tmp:tmp -> tmp73, tmp:tmp -> tmp74, member:Iter -> Iter, tmp:tmp -> tmp75, class:TVar -> TVar, env -> env8, member:instance$Ident(Gen) -> instance$Ident$_Gen$_8, tmp:tmp -> tmp76, tmp:tmp -> tmp77, tmp:inlinedVal -> inlinedVal12, tmp:block$res -> block$res37, class:TPrim -> TPrim, tmp:tmp -> tmp78, member:Runtime -> Runtime, tmp:tmp -> tmp79, tmp:tmp -> tmp80, env -> env9, member:instance$Ident(Gen) -> instance$Ident$_Gen$_9, tmp:tmp -> tmp81, tmp:tmp -> tmp82, tmp:inlinedVal -> inlinedVal13, tmp:block$res -> block$res38, env2 -> env21, tmp:tmp -> tmp83, tmp:tmp -> tmp84, tmp:tmp -> tmp85, tmp:tmp -> tmp86, tmp:block$res -> block$res39, tmp:block$res -> block$res3, tmp:tmp -> tmp87, TInt -> TInt, tmp:tmp -> tmp88, tmp:tmp -> tmp89, TBool -> TBool, tmp:tmp -> tmp90, tmp:tmp -> tmp91, tmp:block$res -> block$res4, env -> env10, member:Term -> Term2, member:IntLit -> IntLit1, member:instance$Ident(Gen) -> instance$Ident$_Gen$_10, member:Var -> Var1, tmp:tmp -> tmp92, member:App -> App1, tmp:tmp -> tmp93, member:Abs -> Abs1, tmp:inlinedVal -> inlinedVal14, member:BoolLit -> BoolLit1, member:ShowTerm -> ShowTerm1, tmp:block$res -> block$res40, pattern:ShowTerm -> ShowTerm, class:Abs -> Abs, tmp:tmp -> tmp94, tmp:tmp -> tmp95, tmp:tmp -> tmp96, tmp:tmp -> tmp97, tmp:tmp -> tmp98, env -> env12, class:App -> App, tmp:block$res -> block$res21, emptyEnv -> emptyEnv, member:instance$Ident(Gen) -> instance$Ident$_Gen$_11, tmp:tmp -> tmp99, tmp:tmp -> tmp29, tmp:tmp -> tmp100, tmp:block$res -> block$res22, tmp:inlinedVal -> inlinedVal15, tmp:block$res -> block$res41, member:Gen -> Gen1, class:Gen -> Gen, class:Term -> Term1, class:Var -> Var, tmp:block$res -> block$res23, class:IntLit -> IntLit, class:BoolLit -> BoolLit, member:lambda$ -> lambda$, member:inferTop -> inferTop, tmp:block$res -> block$res5, member:Scheme -> Scheme1, class:Scheme -> Scheme, tmp:block$res -> block$res24, tmp:block$res -> block$res10, member:unify' -> unify$_, member:inferType -> inferType, tmp:block$res -> block$res11, member:unify -> unify, tmp:block$res -> block$res25, id -> id, const -> const1, apply -> apply, tmp:block$res -> block$res6, compose -> compose, member:Subst -> Subst1, class:Subst -> Subst, tmp:tmp -> tmp30, tmp:tmp -> tmp31, tmp:tmp -> tmp32, tmp:tmp -> tmp33, tmp:tmp -> tmp34, tmp:tmp -> tmp35, tmp:tmp -> tmp36, tmp:tmp -> tmp37, tmp:tmp -> tmp38, tmp:tmp -> tmp39, tmp:tmp -> tmp40, tmp:tmp -> tmp41, tmp:tmp -> tmp42, tmp:tmp -> tmp43, tmp:block$res -> block$res26, tmp:block$res -> block$res27, env -> env, term -> term, member:instance$Ident(Gen) -> instance$Ident$_Gen$_, tmp:tmp -> tmp44, tmp:tmp -> tmp45, tmp:inlinedVal -> inlinedVal4, tmp:block$res -> block$res28, env -> env1)
+//│     defaultImportBindings = HashMap(/storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Iter.mjs -> Iter, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Option.mjs -> Option, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Runtime.mjs -> Runtime, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Predef.mjs -> Predef)
+//│ ═══[COMPILATION ERROR] No definition found in scope for member 'infer$tailrec'
+//│ ═══[RUNTIME ERROR] ReferenceError: infer$tailrec is not defined
 
 :silent
 let env3 = env2.extend of
@@ -328,19 +731,91 @@ let env3 = env2.extend of
   Scheme(new Set(["a"]), TFun(TBool, TFun(TVar("a"), TFun(TVar("a"), TVar("a")))))
 
 env3 |- Var("if")
-//│ = "∀t₀. Bool -> t₀ -> t₀ -> t₀"
+//│ FAILURE: Unexpected compilation error
+//│ FAILURE LOCATION: lookup_! (Scope.scala:136)
+//│ FAILURE INFO: Tuple2:
+//│   _1 = Tuple2:
+//│     _1 = member:infer$tailrec⁰
+//│     _2 = class hkmc2.semantics.BlockMemberSymbol
+//│   _2 = Scope:
+//│     parentOrCfg = Left of Cfg:
+//│       escapeChars = true
+//│       useSuperscripts = false
+//│       includeZero = false
+//│       defaultName = "tmp"
+//│     curThis = S of S of globalThis:globalThis⁰
+//│     bindings = HashMap(term -> term1, member:instance$Ident(Gen) -> instance$Ident$_Gen$_1, tmp:runtime -> runtime, tmp:block$res -> block$res12, tmp:tmp -> tmp46, tmp:definitionMetadata -> definitionMetadata, tmp:tmp -> tmp47, tmp:prettyPrint -> prettyPrint, tmp:inlinedVal -> inlinedVal5, tmp:Term -> Term, tmp:Block -> Block, tmp:tmp -> tmp1, tmp:block$res -> block$res29, tmp:option -> option, tmp:block$res -> block$res13, env -> env2, term -> term2, t1 -> t1, t2 -> t2, member:instance$Ident(Gen) -> instance$Ident$_Gen$_2, tmp:inlinedVal -> inlinedVal, tmp:tmp -> tmp48, tmp:tmp -> tmp49, tmp:tmp -> tmp2, tmp:inlinedVal -> inlinedVal6, tmp:scrut -> scrut, tmp:block$res -> block$res14, tmp:block$res -> block$res30, env -> env3, term -> term3, tmp:tmp -> tmp3, tmp:tmp -> tmp4, tmp:block$res -> block$res15, member:instance$Ident(Gen) -> instance$Ident$_Gen$_3, tmp:tmp -> tmp50, tmp:tmp -> tmp51, tmp:inlinedVal -> inlinedVal7, tmp:tmp -> tmp5, tmp:block$res -> block$res31, t2 -> t21, tmp:inlinedVal -> inlinedVal1, tmp:tmp -> tmp52, env -> env4, tmp:block$res -> block$res, tmp:tmp -> tmp6, tmp:scrut -> scrut1, tmp:block$res -> block$res1, tmp:block$res -> block$res16, member:instance$Ident(Gen) -> instance$Ident$_Gen$_4, tmp:block$res -> block$res2, tmp:tmp -> tmp53, tmp:tmp -> tmp54, tmp:inlinedVal -> inlinedVal8, member:Option -> Option, tmp:block$res -> block$res32, member:Type -> Type1, member:TVar -> TVar1, member:TFun -> TFun1, tmp:tmp -> tmp7, tmp:tmp -> tmp55, member:TPrim -> TPrim1, tmp:tmp -> tmp8, env -> env5, class:Type -> Type, tmp:tmp -> tmp9, tmp:tmp -> tmp10, tmp:tmp -> tmp11, tmp:tmp -> tmp12, member:instance$Ident(Gen) -> instance$Ident$_Gen$_5, class:TFun -> TFun, tmp:tmp -> tmp13, tmp:tmp -> tmp56, tmp:block$res -> block$res17, tmp:tmp -> tmp57, tmp:inlinedVal -> inlinedVal9, tmp:block$res -> block$res33, tmp:tmp -> tmp58, tmp:tmp -> tmp59, tmp:tmp -> tmp14, env -> env6, tmp:tmp -> tmp15, tmp:tmp -> tmp16, tmp:tmp -> tmp17, tmp:tmp -> tmp18, member:instance$Ident(Gen) -> instance$Ident$_Gen$_6, tmp:tmp -> tmp19, tmp:tmp -> tmp60, tmp:tmp -> tmp61, tmp:inlinedVal -> inlinedVal10, tmp:inlinedVal -> inlinedVal2, tmp:block$res -> block$res34, tmp:tmp -> tmp20, tmp:scrut -> scrut2, tmp:block$res -> block$res18, tmp:tmp -> tmp62, tmp:tmp -> tmp63, tmp:tmp -> tmp64, tmp:block$res -> block$res7, env -> env7, emptySub -> emptySub, tmp:tmp -> tmp21, tmp:tmp -> tmp22, tmp:tmp -> tmp23, member:instance$Ident(Gen) -> instance$Ident$_Gen$_7, tmp:tmp -> tmp, tmp:tmp -> tmp24, tmp:tmp -> tmp65, member:Predef -> Predef, tmp:block$res -> block$res8, tmp:block$res -> block$res19, tmp:tmp -> tmp66, tmp:inlinedVal -> inlinedVal11, member:applyPattern -> applyPattern, tmp:block$res -> block$res35, env1 -> env11, tmp:tmp -> tmp25, tmp:tmp -> tmp26, tmp:tmp -> tmp27, tmp:inlinedVal -> inlinedVal3, tmp:tmp -> tmp67, tmp:tmp -> tmp68, tmp:block$res -> block$res9, tmp:tmp -> tmp28, tmp:tmp -> tmp69, tmp:scrut -> scrut3, tmp:tmp -> tmp70, member:Unify -> Unify1, tmp:block$res -> block$res20, tmp:tmp -> tmp71, pattern:Unify -> Unify, tmp:tmp -> tmp72, tmp:block$res -> block$res36, member:Env -> Env1, class:Env -> Env, tmp:tmp -> tmp73, tmp:tmp -> tmp74, member:Iter -> Iter, tmp:tmp -> tmp75, class:TVar -> TVar, env -> env8, member:instance$Ident(Gen) -> instance$Ident$_Gen$_8, tmp:tmp -> tmp76, tmp:tmp -> tmp77, tmp:inlinedVal -> inlinedVal12, tmp:block$res -> block$res37, class:TPrim -> TPrim, tmp:tmp -> tmp78, member:Runtime -> Runtime, tmp:tmp -> tmp79, tmp:tmp -> tmp80, env -> env9, member:instance$Ident(Gen) -> instance$Ident$_Gen$_9, tmp:tmp -> tmp81, tmp:tmp -> tmp82, tmp:inlinedVal -> inlinedVal13, tmp:block$res -> block$res38, env2 -> env21, tmp:tmp -> tmp83, tmp:tmp -> tmp84, tmp:tmp -> tmp85, tmp:tmp -> tmp86, tmp:block$res -> block$res39, tmp:block$res -> block$res3, tmp:tmp -> tmp87, TInt -> TInt, tmp:tmp -> tmp88, tmp:tmp -> tmp89, TBool -> TBool, tmp:tmp -> tmp90, tmp:tmp -> tmp91, tmp:block$res -> block$res4, env -> env10, member:Term -> Term2, member:IntLit -> IntLit1, member:instance$Ident(Gen) -> instance$Ident$_Gen$_10, member:Var -> Var1, tmp:tmp -> tmp92, member:App -> App1, tmp:tmp -> tmp93, member:Abs -> Abs1, tmp:inlinedVal -> inlinedVal14, member:BoolLit -> BoolLit1, member:ShowTerm -> ShowTerm1, tmp:block$res -> block$res40, pattern:ShowTerm -> ShowTerm, class:Abs -> Abs, tmp:tmp -> tmp94, tmp:tmp -> tmp95, tmp:tmp -> tmp96, tmp:tmp -> tmp97, tmp:tmp -> tmp98, env -> env12, class:App -> App, tmp:block$res -> block$res21, emptyEnv -> emptyEnv, member:instance$Ident(Gen) -> instance$Ident$_Gen$_11, tmp:tmp -> tmp99, tmp:tmp -> tmp29, tmp:tmp -> tmp100, tmp:block$res -> block$res22, tmp:inlinedVal -> inlinedVal15, tmp:block$res -> block$res41, member:Gen -> Gen1, env3 -> env31, class:Gen -> Gen, tmp:tmp -> tmp101, tmp:tmp -> tmp102, tmp:tmp -> tmp103, tmp:tmp -> tmp104, tmp:tmp -> tmp105, tmp:tmp -> tmp106, tmp:tmp -> tmp107, class:Term -> Term1, tmp:tmp -> tmp108, tmp:tmp -> tmp109, tmp:block$res -> block$res42, class:Var -> Var, tmp:tmp -> tmp110, env -> env13, member:instance$Ident(Gen) -> instance$Ident$_Gen$_12, tmp:tmp -> tmp111, tmp:tmp -> tmp112, tmp:inlinedVal -> inlinedVal16, tmp:block$res -> block$res43, tmp:block$res -> block$res23, class:IntLit -> IntLit, class:BoolLit -> BoolLit, member:lambda$ -> lambda$, member:inferTop -> inferTop, tmp:block$res -> block$res5, member:Scheme -> Scheme1, class:Scheme -> Scheme, tmp:block$res -> block$res24, tmp:block$res -> block$res10, member:unify' -> unify$_, member:inferType -> inferType, tmp:block$res -> block$res11, member:unify -> unify, tmp:block$res -> block$res25, id -> id, const -> const1, apply -> apply, tmp:block$res -> block$res6, compose -> compose, member:Subst -> Subst1, class:Subst -> Subst, tmp:tmp -> tmp30, tmp:tmp -> tmp31, tmp:tmp -> tmp32, tmp:tmp -> tmp33, tmp:tmp -> tmp34, tmp:tmp -> tmp35, tmp:tmp -> tmp36, tmp:tmp -> tmp37, tmp:tmp -> tmp38, tmp:tmp -> tmp39, tmp:tmp -> tmp40, tmp:tmp -> tmp41, tmp:tmp -> tmp42, tmp:tmp -> tmp43, tmp:block$res -> block$res26, tmp:block$res -> block$res27, env -> env, term -> term, member:instance$Ident(Gen) -> instance$Ident$_Gen$_, tmp:tmp -> tmp44, tmp:tmp -> tmp45, tmp:inlinedVal -> inlinedVal4, tmp:block$res -> block$res28, env -> env1)
+//│     defaultImportBindings = HashMap(/storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Iter.mjs -> Iter, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Option.mjs -> Option, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Runtime.mjs -> Runtime, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Predef.mjs -> Predef)
+//│ ═══[COMPILATION ERROR] No definition found in scope for member 'infer$tailrec'
+//│ FAILURE: Unexpected runtime error
+//│ FAILURE LOCATION: mkQuery (JSBackendDiffMaker.scala:259)
+//│ ═══[RUNTIME ERROR] ReferenceError: infer$tailrec is not defined
+//│     at REPL136:1:239
+//│     at ContextifyScript.runInThisContext (node:vm:138:12)
+//│     at defaultEval (node:repl:608:24)
+//│     at REPLEvalInContext (node:repl:691:9)
+//│     at AsyncLocalStorage.run (node:internal/async_local_storage/async_context_frame:66:14)
+//│     at REPLServer.REPLEval [as eval] (node:repl:690:19)
+//│     at REPLServer.onLine (node:repl:828:12)
+//│     at REPLServer.emit (node:events:514:20)
+//│     at [_onLine] [as _onLine] (node:internal/readline/interface:474:12)
+//│     at [_normalWrite] [as _normalWrite] (node:internal/readline/interface:669:18)
 
 :silent
 let t = App(App(App(Var("if"), BoolLit(true)), App(Var("id"), Var("id"))), Var("id"))
 print of t.show
 print of env3 |- t
+//│ FAILURE: Unexpected compilation error
+//│ FAILURE LOCATION: lookup_! (Scope.scala:136)
+//│ FAILURE INFO: Tuple2:
+//│   _1 = Tuple2:
+//│     _1 = member:infer$tailrec⁰
+//│     _2 = class hkmc2.semantics.BlockMemberSymbol
+//│   _2 = Scope:
+//│     parentOrCfg = Left of Cfg:
+//│       escapeChars = true
+//│       useSuperscripts = false
+//│       includeZero = false
+//│       defaultName = "tmp"
+//│     curThis = S of S of globalThis:globalThis⁰
+//│     bindings = HashMap(term -> term1, member:instance$Ident(Gen) -> instance$Ident$_Gen$_1, tmp:runtime -> runtime, tmp:block$res -> block$res12, tmp:tmp -> tmp46, tmp:definitionMetadata -> definitionMetadata, tmp:tmp -> tmp47, tmp:prettyPrint -> prettyPrint, tmp:inlinedVal -> inlinedVal5, tmp:Term -> Term, tmp:Block -> Block, tmp:tmp -> tmp1, tmp:block$res -> block$res29, tmp:option -> option, tmp:block$res -> block$res13, env -> env2, term -> term2, t1 -> t1, t2 -> t2, member:instance$Ident(Gen) -> instance$Ident$_Gen$_2, tmp:inlinedVal -> inlinedVal, tmp:tmp -> tmp48, tmp:tmp -> tmp49, tmp:tmp -> tmp2, tmp:inlinedVal -> inlinedVal6, tmp:scrut -> scrut, tmp:block$res -> block$res14, tmp:block$res -> block$res30, env -> env3, term -> term3, tmp:tmp -> tmp3, tmp:tmp -> tmp4, tmp:block$res -> block$res15, member:instance$Ident(Gen) -> instance$Ident$_Gen$_3, tmp:tmp -> tmp50, tmp:tmp -> tmp51, tmp:inlinedVal -> inlinedVal7, tmp:tmp -> tmp5, tmp:block$res -> block$res31, t2 -> t21, tmp:inlinedVal -> inlinedVal1, tmp:tmp -> tmp52, env -> env4, tmp:block$res -> block$res, tmp:tmp -> tmp6, tmp:scrut -> scrut1, tmp:block$res -> block$res1, tmp:block$res -> block$res16, member:instance$Ident(Gen) -> instance$Ident$_Gen$_4, tmp:block$res -> block$res2, tmp:tmp -> tmp53, tmp:tmp -> tmp54, tmp:inlinedVal -> inlinedVal8, member:Option -> Option, tmp:block$res -> block$res32, member:Type -> Type1, member:TVar -> TVar1, member:TFun -> TFun1, tmp:tmp -> tmp7, tmp:tmp -> tmp55, member:TPrim -> TPrim1, tmp:tmp -> tmp8, env -> env5, class:Type -> Type, tmp:tmp -> tmp9, tmp:tmp -> tmp10, tmp:tmp -> tmp11, tmp:tmp -> tmp12, member:instance$Ident(Gen) -> instance$Ident$_Gen$_5, class:TFun -> TFun, tmp:tmp -> tmp13, tmp:tmp -> tmp56, tmp:block$res -> block$res17, tmp:tmp -> tmp57, tmp:inlinedVal -> inlinedVal9, tmp:block$res -> block$res33, tmp:tmp -> tmp58, tmp:tmp -> tmp59, tmp:tmp -> tmp14, env -> env6, tmp:tmp -> tmp15, tmp:tmp -> tmp16, tmp:tmp -> tmp17, tmp:tmp -> tmp18, member:instance$Ident(Gen) -> instance$Ident$_Gen$_6, tmp:tmp -> tmp19, tmp:tmp -> tmp60, tmp:tmp -> tmp61, tmp:inlinedVal -> inlinedVal10, tmp:inlinedVal -> inlinedVal2, tmp:block$res -> block$res34, tmp:tmp -> tmp20, tmp:scrut -> scrut2, tmp:block$res -> block$res18, tmp:tmp -> tmp62, tmp:tmp -> tmp63, tmp:tmp -> tmp64, tmp:block$res -> block$res7, env -> env7, emptySub -> emptySub, tmp:tmp -> tmp21, tmp:tmp -> tmp22, tmp:tmp -> tmp23, member:instance$Ident(Gen) -> instance$Ident$_Gen$_7, tmp:tmp -> tmp, tmp:tmp -> tmp24, tmp:tmp -> tmp65, member:Predef -> Predef, tmp:block$res -> block$res8, tmp:block$res -> block$res19, tmp:tmp -> tmp66, tmp:inlinedVal -> inlinedVal11, member:applyPattern -> applyPattern, tmp:block$res -> block$res35, env1 -> env11, tmp:tmp -> tmp25, tmp:tmp -> tmp26, tmp:tmp -> tmp27, tmp:inlinedVal -> inlinedVal3, tmp:tmp -> tmp67, tmp:tmp -> tmp68, tmp:block$res -> block$res9, tmp:tmp -> tmp28, tmp:tmp -> tmp69, tmp:scrut -> scrut3, tmp:tmp -> tmp70, member:Unify -> Unify1, tmp:block$res -> block$res20, tmp:tmp -> tmp71, pattern:Unify -> Unify, tmp:tmp -> tmp72, tmp:block$res -> block$res36, member:Env -> Env1, class:Env -> Env, tmp:tmp -> tmp73, tmp:tmp -> tmp74, member:Iter -> Iter, tmp:tmp -> tmp75, class:TVar -> TVar, env -> env8, member:instance$Ident(Gen) -> instance$Ident$_Gen$_8, tmp:tmp -> tmp76, tmp:tmp -> tmp77, tmp:inlinedVal -> inlinedVal12, tmp:block$res -> block$res37, class:TPrim -> TPrim, tmp:tmp -> tmp78, member:Runtime -> Runtime, tmp:tmp -> tmp79, tmp:tmp -> tmp80, env -> env9, member:instance$Ident(Gen) -> instance$Ident$_Gen$_9, tmp:tmp -> tmp81, tmp:tmp -> tmp82, tmp:inlinedVal -> inlinedVal13, tmp:block$res -> block$res38, env2 -> env21, tmp:tmp -> tmp83, tmp:tmp -> tmp84, tmp:tmp -> tmp85, tmp:tmp -> tmp86, tmp:block$res -> block$res39, tmp:block$res -> block$res3, tmp:tmp -> tmp87, TInt -> TInt, tmp:tmp -> tmp88, tmp:tmp -> tmp89, TBool -> TBool, tmp:tmp -> tmp90, tmp:tmp -> tmp91, tmp:block$res -> block$res4, env -> env10, member:Term -> Term2, member:IntLit -> IntLit1, member:instance$Ident(Gen) -> instance$Ident$_Gen$_10, member:Var -> Var1, tmp:tmp -> tmp92, member:App -> App1, tmp:tmp -> tmp93, member:Abs -> Abs1, tmp:inlinedVal -> inlinedVal14, member:BoolLit -> BoolLit1, member:ShowTerm -> ShowTerm1, tmp:block$res -> block$res40, pattern:ShowTerm -> ShowTerm, class:Abs -> Abs, tmp:tmp -> tmp94, tmp:tmp -> tmp95, tmp:tmp -> tmp96, tmp:tmp -> tmp97, tmp:tmp -> tmp98, env -> env12, class:App -> App, tmp:block$res -> block$res21, emptyEnv -> emptyEnv, member:instance$Ident(Gen) -> instance$Ident$_Gen$_11, tmp:tmp -> tmp99, tmp:tmp -> tmp29, tmp:tmp -> tmp100, tmp:block$res -> block$res22, tmp:inlinedVal -> inlinedVal15, tmp:block$res -> block$res41, member:Gen -> Gen1, env3 -> env31, class:Gen -> Gen, tmp:tmp -> tmp101, tmp:tmp -> tmp102, tmp:tmp -> tmp103, tmp:tmp -> tmp104, tmp:tmp -> tmp105, tmp:tmp -> tmp106, tmp:tmp -> tmp107, class:Term -> Term1, tmp:tmp -> tmp108, tmp:tmp -> tmp109, tmp:block$res -> block$res42, class:Var -> Var, tmp:tmp -> tmp110, env -> env13, member:instance$Ident(Gen) -> instance$Ident$_Gen$_12, tmp:tmp -> tmp111, tmp:tmp -> tmp112, tmp:inlinedVal -> inlinedVal16, tmp:block$res -> block$res43, t -> t, tmp:block$res -> block$res23, class:IntLit -> IntLit, class:BoolLit -> BoolLit, tmp:tmp -> tmp113, tmp:tmp -> tmp114, tmp:tmp -> tmp115, tmp:tmp -> tmp116, tmp:tmp -> tmp117, tmp:tmp -> tmp118, tmp:tmp -> tmp119, tmp:tmp -> tmp120, env -> env14, term -> term4, tmp:inlinedVal -> inlinedVal17, member:instance$Ident(Gen) -> instance$Ident$_Gen$_13, tmp:tmp -> tmp121, tmp:tmp -> tmp122, tmp:inlinedVal -> inlinedVal18, tmp:block$res -> block$res44, member:lambda$ -> lambda$, member:inferTop -> inferTop, tmp:block$res -> block$res5, member:Scheme -> Scheme1, class:Scheme -> Scheme, tmp:block$res -> block$res24, tmp:block$res -> block$res10, member:unify' -> unify$_, member:inferType -> inferType, tmp:block$res -> block$res11, member:unify -> unify, tmp:block$res -> block$res25, id -> id, const -> const1, apply -> apply, tmp:block$res -> block$res6, compose -> compose, member:Subst -> Subst1, class:Subst -> Subst, tmp:tmp -> tmp30, tmp:tmp -> tmp31, tmp:tmp -> tmp32, tmp:tmp -> tmp33, tmp:tmp -> tmp34, tmp:tmp -> tmp35, tmp:tmp -> tmp36, tmp:tmp -> tmp37, tmp:tmp -> tmp38, tmp:tmp -> tmp39, tmp:tmp -> tmp40, tmp:tmp -> tmp41, tmp:tmp -> tmp42, tmp:tmp -> tmp43, tmp:block$res -> block$res26, tmp:block$res -> block$res27, env -> env, term -> term, member:instance$Ident(Gen) -> instance$Ident$_Gen$_, tmp:tmp -> tmp44, tmp:tmp -> tmp45, tmp:inlinedVal -> inlinedVal4, tmp:block$res -> block$res28, env -> env1)
+//│     defaultImportBindings = HashMap(/storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Iter.mjs -> Iter, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Option.mjs -> Option, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Runtime.mjs -> Runtime, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Predef.mjs -> Predef)
+//│ ═══[COMPILATION ERROR] No definition found in scope for member 'infer$tailrec'
 //│ > if true (id id) id
-//│ > ∀t₆. t₆ -> t₆
+//│ FAILURE: Unexpected runtime error
+//│ FAILURE LOCATION: mkQuery (JSBackendDiffMaker.scala:259)
+//│ ═══[RUNTIME ERROR] ReferenceError: infer$tailrec is not defined
+//│     at REPL139:1:762
+//│     at ContextifyScript.runInThisContext (node:vm:138:12)
+//│     at defaultEval (node:repl:608:24)
+//│     at REPLEvalInContext (node:repl:691:9)
+//│     at AsyncLocalStorage.run (node:internal/async_local_storage/async_context_frame:66:14)
+//│     at REPLServer.REPLEval [as eval] (node:repl:690:19)
+//│     at REPLServer.onLine (node:repl:828:12)
+//│     at REPLServer.emit (node:events:514:20)
+//│     at [_onLine] [as _onLine] (node:internal/readline/interface:474:12)
+//│     at [_normalWrite] [as _normalWrite] (node:internal/readline/interface:669:18)
 
 :silent
 :re
 let t = App(App(App(Var("if"), BoolLit(true)), App(Var("id"), Var("id"))), Var("add"))
 print of t.show
 print of env3 |- t
+//│ FAILURE: Unexpected compilation error
+//│ FAILURE LOCATION: lookup_! (Scope.scala:136)
+//│ FAILURE INFO: Tuple2:
+//│   _1 = Tuple2:
+//│     _1 = member:infer$tailrec⁰
+//│     _2 = class hkmc2.semantics.BlockMemberSymbol
+//│   _2 = Scope:
+//│     parentOrCfg = Left of Cfg:
+//│       escapeChars = true
+//│       useSuperscripts = false
+//│       includeZero = false
+//│       defaultName = "tmp"
+//│     curThis = S of S of globalThis:globalThis⁰
+//│     bindings = HashMap(term -> term1, member:instance$Ident(Gen) -> instance$Ident$_Gen$_1, tmp:runtime -> runtime, tmp:block$res -> block$res12, tmp:tmp -> tmp46, tmp:definitionMetadata -> definitionMetadata, tmp:tmp -> tmp47, tmp:prettyPrint -> prettyPrint, tmp:inlinedVal -> inlinedVal5, tmp:Term -> Term, tmp:Block -> Block, tmp:tmp -> tmp1, tmp:block$res -> block$res29, tmp:option -> option, tmp:block$res -> block$res13, env -> env2, term -> term2, t1 -> t1, t2 -> t2, member:instance$Ident(Gen) -> instance$Ident$_Gen$_2, tmp:inlinedVal -> inlinedVal, tmp:tmp -> tmp48, tmp:tmp -> tmp49, tmp:tmp -> tmp2, tmp:inlinedVal -> inlinedVal6, tmp:scrut -> scrut, tmp:block$res -> block$res14, tmp:block$res -> block$res30, env -> env3, term -> term3, tmp:tmp -> tmp3, tmp:tmp -> tmp4, tmp:block$res -> block$res15, member:instance$Ident(Gen) -> instance$Ident$_Gen$_3, tmp:tmp -> tmp50, tmp:tmp -> tmp51, tmp:inlinedVal -> inlinedVal7, tmp:tmp -> tmp5, tmp:block$res -> block$res31, t2 -> t21, tmp:inlinedVal -> inlinedVal1, tmp:tmp -> tmp52, env -> env4, tmp:block$res -> block$res, tmp:tmp -> tmp6, tmp:scrut -> scrut1, tmp:block$res -> block$res1, tmp:block$res -> block$res16, member:instance$Ident(Gen) -> instance$Ident$_Gen$_4, tmp:block$res -> block$res2, tmp:tmp -> tmp53, tmp:tmp -> tmp54, tmp:inlinedVal -> inlinedVal8, member:Option -> Option, tmp:block$res -> block$res32, member:Type -> Type1, member:TVar -> TVar1, member:TFun -> TFun1, tmp:tmp -> tmp7, tmp:tmp -> tmp55, member:TPrim -> TPrim1, tmp:tmp -> tmp8, env -> env5, class:Type -> Type, tmp:tmp -> tmp9, tmp:tmp -> tmp10, tmp:tmp -> tmp11, tmp:tmp -> tmp12, member:instance$Ident(Gen) -> instance$Ident$_Gen$_5, class:TFun -> TFun, tmp:tmp -> tmp13, tmp:tmp -> tmp56, tmp:block$res -> block$res17, tmp:tmp -> tmp57, tmp:inlinedVal -> inlinedVal9, tmp:block$res -> block$res33, tmp:tmp -> tmp58, tmp:tmp -> tmp59, tmp:tmp -> tmp14, env -> env6, tmp:tmp -> tmp15, tmp:tmp -> tmp16, tmp:tmp -> tmp17, tmp:tmp -> tmp18, member:instance$Ident(Gen) -> instance$Ident$_Gen$_6, tmp:tmp -> tmp19, tmp:tmp -> tmp60, tmp:tmp -> tmp61, tmp:inlinedVal -> inlinedVal10, tmp:inlinedVal -> inlinedVal2, tmp:block$res -> block$res34, tmp:tmp -> tmp20, tmp:scrut -> scrut2, tmp:block$res -> block$res18, tmp:tmp -> tmp62, tmp:tmp -> tmp63, tmp:tmp -> tmp64, tmp:block$res -> block$res7, env -> env7, emptySub -> emptySub, tmp:tmp -> tmp21, tmp:tmp -> tmp22, tmp:tmp -> tmp23, member:instance$Ident(Gen) -> instance$Ident$_Gen$_7, tmp:tmp -> tmp, tmp:tmp -> tmp24, tmp:tmp -> tmp65, member:Predef -> Predef, tmp:block$res -> block$res8, tmp:block$res -> block$res19, tmp:tmp -> tmp66, tmp:inlinedVal -> inlinedVal11, member:applyPattern -> applyPattern, tmp:block$res -> block$res35, env1 -> env11, tmp:tmp -> tmp25, tmp:tmp -> tmp26, tmp:tmp -> tmp27, tmp:inlinedVal -> inlinedVal3, tmp:tmp -> tmp67, tmp:tmp -> tmp68, tmp:block$res -> block$res9, tmp:tmp -> tmp28, tmp:tmp -> tmp69, tmp:scrut -> scrut3, tmp:tmp -> tmp70, member:Unify -> Unify1, tmp:block$res -> block$res20, tmp:tmp -> tmp71, pattern:Unify -> Unify, tmp:tmp -> tmp72, tmp:block$res -> block$res36, member:Env -> Env1, class:Env -> Env, tmp:tmp -> tmp73, tmp:tmp -> tmp74, member:Iter -> Iter, tmp:tmp -> tmp75, class:TVar -> TVar, env -> env8, member:instance$Ident(Gen) -> instance$Ident$_Gen$_8, tmp:tmp -> tmp76, tmp:tmp -> tmp77, tmp:inlinedVal -> inlinedVal12, tmp:block$res -> block$res37, class:TPrim -> TPrim, tmp:tmp -> tmp78, member:Runtime -> Runtime, tmp:tmp -> tmp79, tmp:tmp -> tmp80, env -> env9, member:instance$Ident(Gen) -> instance$Ident$_Gen$_9, tmp:tmp -> tmp81, tmp:tmp -> tmp82, tmp:inlinedVal -> inlinedVal13, tmp:block$res -> block$res38, env2 -> env21, tmp:tmp -> tmp83, tmp:tmp -> tmp84, tmp:tmp -> tmp85, tmp:tmp -> tmp86, tmp:block$res -> block$res39, tmp:block$res -> block$res3, tmp:tmp -> tmp87, TInt -> TInt, tmp:tmp -> tmp88, tmp:tmp -> tmp89, TBool -> TBool, tmp:tmp -> tmp90, tmp:tmp -> tmp91, tmp:block$res -> block$res4, env -> env10, member:Term -> Term2, member:IntLit -> IntLit1, member:instance$Ident(Gen) -> instance$Ident$_Gen$_10, member:Var -> Var1, tmp:tmp -> tmp92, member:App -> App1, tmp:tmp -> tmp93, member:Abs -> Abs1, tmp:inlinedVal -> inlinedVal14, member:BoolLit -> BoolLit1, member:ShowTerm -> ShowTerm1, tmp:block$res -> block$res40, pattern:ShowTerm -> ShowTerm, class:Abs -> Abs, tmp:tmp -> tmp94, tmp:tmp -> tmp95, tmp:tmp -> tmp96, tmp:tmp -> tmp97, tmp:tmp -> tmp98, env -> env12, class:App -> App, tmp:block$res -> block$res21, emptyEnv -> emptyEnv, member:instance$Ident(Gen) -> instance$Ident$_Gen$_11, tmp:tmp -> tmp99, tmp:tmp -> tmp29, tmp:tmp -> tmp100, tmp:block$res -> block$res22, tmp:inlinedVal -> inlinedVal15, tmp:block$res -> block$res41, member:Gen -> Gen1, env3 -> env31, class:Gen -> Gen, tmp:tmp -> tmp101, tmp:tmp -> tmp102, tmp:tmp -> tmp103, tmp:tmp -> tmp104, tmp:tmp -> tmp105, tmp:tmp -> tmp106, tmp:tmp -> tmp107, class:Term -> Term1, tmp:tmp -> tmp108, tmp:tmp -> tmp109, tmp:block$res -> block$res42, class:Var -> Var, tmp:tmp -> tmp110, env -> env13, member:instance$Ident(Gen) -> instance$Ident$_Gen$_12, tmp:tmp -> tmp111, tmp:tmp -> tmp112, tmp:inlinedVal -> inlinedVal16, tmp:block$res -> block$res43, t -> t, tmp:block$res -> block$res23, class:IntLit -> IntLit, class:BoolLit -> BoolLit, tmp:tmp -> tmp113, tmp:tmp -> tmp114, tmp:tmp -> tmp115, tmp:tmp -> tmp116, tmp:tmp -> tmp117, tmp:tmp -> tmp118, tmp:tmp -> tmp119, tmp:tmp -> tmp120, env -> env14, term -> term4, tmp:inlinedVal -> inlinedVal17, member:instance$Ident(Gen) -> instance$Ident$_Gen$_13, tmp:tmp -> tmp121, tmp:tmp -> tmp122, tmp:inlinedVal -> inlinedVal18, tmp:block$res -> block$res44, t -> t3, member:lambda$ -> lambda$, tmp:tmp -> tmp123, tmp:tmp -> tmp124, tmp:tmp -> tmp125, tmp:tmp -> tmp126, tmp:tmp -> tmp127, tmp:tmp -> tmp128, tmp:tmp -> tmp129, tmp:tmp -> tmp130, env -> env15, term -> term5, tmp:inlinedVal -> inlinedVal19, member:instance$Ident(Gen) -> instance$Ident$_Gen$_14, tmp:tmp -> tmp131, tmp:tmp -> tmp132, tmp:inlinedVal -> inlinedVal20, tmp:block$res -> block$res45, member:inferTop -> inferTop, tmp:block$res -> block$res5, member:Scheme -> Scheme1, class:Scheme -> Scheme, tmp:block$res -> block$res24, tmp:block$res -> block$res10, member:unify' -> unify$_, member:inferType -> inferType, tmp:block$res -> block$res11, member:unify -> unify, tmp:block$res -> block$res25, id -> id, const -> const1, apply -> apply, tmp:block$res -> block$res6, compose -> compose, member:Subst -> Subst1, class:Subst -> Subst, tmp:tmp -> tmp30, tmp:tmp -> tmp31, tmp:tmp -> tmp32, tmp:tmp -> tmp33, tmp:tmp -> tmp34, tmp:tmp -> tmp35, tmp:tmp -> tmp36, tmp:tmp -> tmp37, tmp:tmp -> tmp38, tmp:tmp -> tmp39, tmp:tmp -> tmp40, tmp:tmp -> tmp41, tmp:tmp -> tmp42, tmp:tmp -> tmp43, tmp:block$res -> block$res26, tmp:block$res -> block$res27, env -> env, term -> term, member:instance$Ident(Gen) -> instance$Ident$_Gen$_, tmp:tmp -> tmp44, tmp:tmp -> tmp45, tmp:inlinedVal -> inlinedVal4, tmp:block$res -> block$res28, env -> env1)
+//│     defaultImportBindings = HashMap(/storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Iter.mjs -> Iter, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Option.mjs -> Option, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Runtime.mjs -> Runtime, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Predef.mjs -> Predef)
+//│ ═══[COMPILATION ERROR] No definition found in scope for member 'infer$tailrec'
 //│ > if true (id id) add
-//│ ═══[RUNTIME ERROR] Error: Cannot unify Int with Int -> Int
+//│ ═══[RUNTIME ERROR] ReferenceError: infer$tailrec is not defined

From 94e31ba89ded26dfc7877b956d9c4ba90360a903 Mon Sep 17 00:00:00 2001
From: CAG2Mark <git@markng.com>
Date: Thu, 27 Aug 2026 17:14:41 +0800
Subject: [PATCH 06/13] use hasWrapper, update tests

---
 .../main/scala/hkmc2/codegen/TailRecOpt.scala |   2 +-
 .../mlscript/ups/examples/HindleyMilner.mls   | 505 +-----------------
 2 files changed, 16 insertions(+), 491 deletions(-)

diff --git a/hkmc2/shared/src/main/scala/hkmc2/codegen/TailRecOpt.scala b/hkmc2/shared/src/main/scala/hkmc2/codegen/TailRecOpt.scala
index f07dc3599a..3f643eeb17 100644
--- a/hkmc2/shared/src/main/scala/hkmc2/codegen/TailRecOpt.scala
+++ b/hkmc2/shared/src/main/scala/hkmc2/codegen/TailRecOpt.scala
@@ -337,7 +337,7 @@ class TailRecOpt(checkAnnotations: Bool)(using State, TL, Raise):
       // Multiple functions: Create a wrapper.
       else (true, BlockMemberSymbol(funs.iterator.map(_.sym.nme).mkString("_"), Nil, true))
     val dSym =
-      if bms is funs.head.sym then funs.head.dSym
+      if !hasWrapper then funs.head.dSym
       else TermSymbol(syntax.Fun, owner, Tree.Ident(bms.nme))
     
     val maxParamLen = maxInt(funs, paramsLen)
diff --git a/hkmc2/shared/src/test/mlscript/ups/examples/HindleyMilner.mls b/hkmc2/shared/src/test/mlscript/ups/examples/HindleyMilner.mls
index 1fb2c2bd7e..b71a15d0ed 100644
--- a/hkmc2/shared/src/test/mlscript/ups/examples/HindleyMilner.mls
+++ b/hkmc2/shared/src/test/mlscript/ups/examples/HindleyMilner.mls
@@ -243,76 +243,15 @@ fun infer(env, term)(using gen: Gen) = if term is
     let tv = gen.fresh
     let env1 = env.extend(name, Scheme(new Set([]), tv))
     infer(env1, body) is [s, t] then [s, TFun(s.apply(tv), t)]
-//│ FAILURE: Unexpected exception
-//│ /!!!\ Uncaught error: java.lang.AssertionError: assertion failed
-//│ 	at: scala.runtime.Scala3RunTime$.assertFailed(Scala3RunTime.scala:13)
-//│ 	at: hkmc2.TailRecOpt$FunRewriter$1.applyResult(TailRecOpt.scala:551)
-//│ 	at: hkmc2.codegen.BlockTransformer.applyBlock(BlockTransformer.scala:83)
-//│ 	at: hkmc2.TailRecOpt$FunRewriter$1.applyBlock(TailRecOpt.scala:522)
-//│ 	at: hkmc2.codegen.BlockTransformer.applySubBlock(BlockTransformer.scala:29)
-//│ 	at: hkmc2.codegen.BlockTransformer.applyBlock$$anonfun$4(BlockTransformer.scala:85)
-//│ 	at: hkmc2.codegen.BlockTransformer.applyPath$$anonfun$2(BlockTransformer.scala:190)
-//│ 	at: hkmc2.codegen.BlockTransformer.applyValue(BlockTransformer.scala:196)
-//│ 	at: hkmc2.codegen.BlockTransformer.applyPath(BlockTransformer.scala:191)
-//│ 	at: hkmc2.codegen.BlockTransformer.applyPath(BlockTransformer.scala:188)
 
 // Type inference with generalization
 fun inferTop(env, name, term)(using Gen) =
   if infer(env, term) is [subst, typ] then...
   [subst, env.generalize(typ)]
-//│ FAILURE: Unexpected compilation error
-//│ FAILURE LOCATION: lookup_! (Scope.scala:136)
-//│ FAILURE INFO: Tuple2:
-//│   _1 = Tuple2:
-//│     _1 = member:infer$tailrec⁰
-//│     _2 = class hkmc2.semantics.BlockMemberSymbol
-//│   _2 = Scope:
-//│     parentOrCfg = Right of Scope:
-//│       parentOrCfg = Right of Scope:
-//│         parentOrCfg = Right of Scope:
-//│           parentOrCfg = Left of Cfg:
-//│             escapeChars = true
-//│             useSuperscripts = false
-//│             includeZero = false
-//│             defaultName = "tmp"
-//│           curThis = S of S of globalThis:globalThis⁰
-//│           bindings = HashMap(tmp:runtime -> runtime, tmp:block$res -> block$res12, tmp:definitionMetadata -> definitionMetadata, tmp:prettyPrint -> prettyPrint, tmp:Term -> Term, tmp:Block -> Block, tmp:tmp -> tmp1, tmp:option -> option, tmp:block$res -> block$res13, t1 -> t1, t2 -> t2, tmp:inlinedVal -> inlinedVal, tmp:tmp -> tmp2, tmp:scrut -> scrut, tmp:block$res -> block$res14, tmp:tmp -> tmp3, tmp:tmp -> tmp4, tmp:block$res -> block$res15, tmp:tmp -> tmp5, t2 -> t21, tmp:inlinedVal -> inlinedVal1, member:lambda$ -> lambda$, tmp:block$res -> block$res, tmp:tmp -> tmp6, tmp:scrut -> scrut1, tmp:block$res -> block$res1, tmp:block$res -> block$res16, tmp:block$res -> block$res2, member:Option -> Option, member:Type -> Type1, member:TVar -> TVar1, member:TFun -> TFun1, tmp:tmp -> tmp7, member:TPrim -> TPrim1, tmp:tmp -> tmp8, class:Type -> Type, tmp:tmp -> tmp9, tmp:tmp -> tmp10, tmp:tmp -> tmp11, tmp:tmp -> tmp12, class:TFun -> TFun, tmp:tmp -> tmp13, tmp:block$res -> block$res17, tmp:tmp -> tmp14, tmp:tmp -> tmp15, tmp:tmp -> tmp16, tmp:tmp -> tmp17, tmp:tmp -> tmp18, tmp:tmp -> tmp19, tmp:inlinedVal -> inlinedVal2, tmp:tmp -> tmp20, tmp:scrut -> scrut2, tmp:block$res -> block$res18, tmp:block$res -> block$res7, emptySub -> emptySub, tmp:tmp -> tmp21, tmp:tmp -> tmp22, tmp:tmp -> tmp23, tmp:tmp -> tmp, tmp:tmp -> tmp24, member:Predef -> Predef, tmp:block$res -> block$res8, tmp:block$res -> block$res19, member:applyPattern -> applyPattern, tmp:tmp -> tmp25, tmp:tmp -> tmp26, tmp:tmp -> tmp27, tmp:inlinedVal -> inlinedVal3, tmp:block$res -> block$res9, tmp:tmp -> tmp28, tmp:scrut -> scrut3, member:Unify -> Unify1, tmp:block$res -> block$res20, pattern:Unify -> Unify, member:Env -> Env1, class:Env -> Env, member:Iter -> Iter, class:TVar -> TVar, class:TPrim -> TPrim, member:Runtime -> Runtime, member:inferTop -> inferTop, tmp:block$res -> block$res5, member:Scheme -> Scheme1, class:Scheme -> Scheme, tmp:block$res -> block$res24, tmp:block$res -> block$res10, member:unify' -> unify$_, tmp:block$res -> block$res3, TInt -> TInt, TBool -> TBool, tmp:block$res -> block$res4, member:Term -> Term2, member:IntLit -> IntLit1, member:Var -> Var1, member:App -> App1, tmp:block$res -> block$res11, member:Abs -> Abs1, member:BoolLit -> BoolLit1, member:unify -> unify, member:ShowTerm -> ShowTerm1, pattern:ShowTerm -> ShowTerm, class:Abs -> Abs, class:App -> App, tmp:block$res -> block$res21, emptyEnv -> emptyEnv, tmp:block$res -> block$res6, tmp:tmp -> tmp29, tmp:block$res -> block$res22, member:Subst -> Subst1, class:Subst -> Subst, member:Gen -> Gen1, class:Gen -> Gen, class:Term -> Term1, class:Var -> Var, tmp:block$res -> block$res23, class:IntLit -> IntLit, class:BoolLit -> BoolLit)
-//│           defaultImportBindings = HashMap(/storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Iter.mjs -> Iter, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Option.mjs -> Option, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Runtime.mjs -> Runtime, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Predef.mjs -> Predef)
-//│         curThis = S of N
-//│         bindings = HashMap(env -> env, name -> name, term -> term)
-//│         defaultImportBindings = HashMap()
-//│       bindings = HashMap( -> tmp30)
-//│       defaultImportBindings = HashMap()
-//│     bindings = HashMap(tmp:inlinedVal -> inlinedVal4, tmp:element1$ -> element1$, tmp:element0$ -> element0$, tmp:tmp -> tmp31)
-//│     defaultImportBindings = HashMap()
-//│ ═══[COMPILATION ERROR] No definition found in scope for member 'infer$tailrec'
 
 fun (|-) inferType(env, term) =
   using Gen = new Gen
   env.generalize(infer(env, term).1).show
-//│ FAILURE: Unexpected compilation error
-//│ FAILURE LOCATION: lookup_! (Scope.scala:136)
-//│ FAILURE INFO: Tuple2:
-//│   _1 = Tuple2:
-//│     _1 = member:infer$tailrec⁰
-//│     _2 = class hkmc2.semantics.BlockMemberSymbol
-//│   _2 = Scope:
-//│     parentOrCfg = Right of Scope:
-//│       parentOrCfg = Right of Scope:
-//│         parentOrCfg = Left of Cfg:
-//│           escapeChars = true
-//│           useSuperscripts = false
-//│           includeZero = false
-//│           defaultName = "tmp"
-//│         curThis = S of S of globalThis:globalThis⁰
-//│         bindings = HashMap(tmp:runtime -> runtime, tmp:block$res -> block$res12, tmp:definitionMetadata -> definitionMetadata, tmp:prettyPrint -> prettyPrint, tmp:Term -> Term, tmp:Block -> Block, tmp:tmp -> tmp1, tmp:option -> option, tmp:block$res -> block$res13, t1 -> t1, t2 -> t2, tmp:inlinedVal -> inlinedVal, tmp:tmp -> tmp2, tmp:scrut -> scrut, tmp:block$res -> block$res14, tmp:tmp -> tmp3, tmp:tmp -> tmp4, tmp:block$res -> block$res15, tmp:tmp -> tmp5, t2 -> t21, tmp:inlinedVal -> inlinedVal1, member:lambda$ -> lambda$, tmp:block$res -> block$res, tmp:tmp -> tmp6, tmp:scrut -> scrut1, tmp:block$res -> block$res1, tmp:block$res -> block$res16, tmp:block$res -> block$res2, member:Option -> Option, member:Type -> Type1, member:TVar -> TVar1, member:TFun -> TFun1, tmp:tmp -> tmp7, member:TPrim -> TPrim1, tmp:tmp -> tmp8, class:Type -> Type, tmp:tmp -> tmp9, tmp:tmp -> tmp10, tmp:tmp -> tmp11, tmp:tmp -> tmp12, class:TFun -> TFun, tmp:tmp -> tmp13, tmp:block$res -> block$res17, tmp:tmp -> tmp14, tmp:tmp -> tmp15, tmp:tmp -> tmp16, tmp:tmp -> tmp17, tmp:tmp -> tmp18, tmp:tmp -> tmp19, tmp:inlinedVal -> inlinedVal2, tmp:tmp -> tmp20, tmp:scrut -> scrut2, tmp:block$res -> block$res18, tmp:block$res -> block$res7, emptySub -> emptySub, tmp:tmp -> tmp21, tmp:tmp -> tmp22, tmp:tmp -> tmp23, tmp:tmp -> tmp, tmp:tmp -> tmp24, member:Predef -> Predef, tmp:block$res -> block$res8, tmp:block$res -> block$res19, member:applyPattern -> applyPattern, tmp:tmp -> tmp25, tmp:tmp -> tmp26, tmp:tmp -> tmp27, tmp:inlinedVal -> inlinedVal3, tmp:block$res -> block$res9, tmp:tmp -> tmp28, tmp:scrut -> scrut3, member:Unify -> Unify1, tmp:block$res -> block$res20, pattern:Unify -> Unify, member:Env -> Env1, class:Env -> Env, member:Iter -> Iter, class:TVar -> TVar, class:TPrim -> TPrim, member:Runtime -> Runtime, member:inferTop -> inferTop, tmp:block$res -> block$res5, member:Scheme -> Scheme1, class:Scheme -> Scheme, tmp:block$res -> block$res24, tmp:block$res -> block$res10, member:unify' -> unify$_, member:inferType -> inferType, tmp:block$res -> block$res3, TInt -> TInt, TBool -> TBool, tmp:block$res -> block$res4, member:Term -> Term2, member:IntLit -> IntLit1, member:Var -> Var1, member:App -> App1, tmp:block$res -> block$res11, member:Abs -> Abs1, member:BoolLit -> BoolLit1, member:unify -> unify, member:ShowTerm -> ShowTerm1, pattern:ShowTerm -> ShowTerm, class:Abs -> Abs, tmp:block$res -> block$res25, class:App -> App, tmp:block$res -> block$res21, emptyEnv -> emptyEnv, tmp:block$res -> block$res6, tmp:tmp -> tmp29, tmp:block$res -> block$res22, member:Subst -> Subst1, class:Subst -> Subst, member:Gen -> Gen1, class:Gen -> Gen, class:Term -> Term1, class:Var -> Var, tmp:block$res -> block$res23, class:IntLit -> IntLit, class:BoolLit -> BoolLit)
-//│         defaultImportBindings = HashMap(/storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Iter.mjs -> Iter, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Option.mjs -> Option, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Runtime.mjs -> Runtime, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Predef.mjs -> Predef)
-//│       curThis = S of N
-//│       bindings = HashMap(env -> env, term -> term)
-//│       defaultImportBindings = HashMap()
-//│     bindings = HashMap(member:instance$Ident(Gen) -> instance$Ident$_Gen$_, tmp:tmp -> tmp30, tmp:tmp -> tmp31, tmp:inlinedVal -> inlinedVal4)
-//│     defaultImportBindings = HashMap()
-//│ ═══[COMPILATION ERROR] No definition found in scope for member 'infer$tailrec'
 
 :silent
 // Example terms
@@ -331,268 +270,32 @@ print of compose.show
 //│ > λf. λg. λx. f (g x)
 
 emptyEnv |- id
-//│ FAILURE: Unexpected compilation error
-//│ FAILURE LOCATION: lookup_! (Scope.scala:136)
-//│ FAILURE INFO: Tuple2:
-//│   _1 = Tuple2:
-//│     _1 = member:infer$tailrec⁰
-//│     _2 = class hkmc2.semantics.BlockMemberSymbol
-//│   _2 = Scope:
-//│     parentOrCfg = Left of Cfg:
-//│       escapeChars = true
-//│       useSuperscripts = false
-//│       includeZero = false
-//│       defaultName = "tmp"
-//│     curThis = S of S of globalThis:globalThis⁰
-//│     bindings = HashMap(tmp:runtime -> runtime, tmp:block$res -> block$res12, tmp:definitionMetadata -> definitionMetadata, tmp:prettyPrint -> prettyPrint, tmp:Term -> Term, tmp:Block -> Block, tmp:tmp -> tmp1, tmp:option -> option, tmp:block$res -> block$res13, t1 -> t1, t2 -> t2, tmp:inlinedVal -> inlinedVal, tmp:tmp -> tmp2, tmp:scrut -> scrut, tmp:block$res -> block$res14, tmp:tmp -> tmp3, tmp:tmp -> tmp4, tmp:block$res -> block$res15, tmp:tmp -> tmp5, t2 -> t21, tmp:inlinedVal -> inlinedVal1, member:lambda$ -> lambda$, tmp:block$res -> block$res, tmp:tmp -> tmp6, tmp:scrut -> scrut1, tmp:block$res -> block$res1, tmp:block$res -> block$res16, tmp:block$res -> block$res2, member:Option -> Option, member:Type -> Type1, member:TVar -> TVar1, member:TFun -> TFun1, tmp:tmp -> tmp7, member:TPrim -> TPrim1, tmp:tmp -> tmp8, class:Type -> Type, tmp:tmp -> tmp9, tmp:tmp -> tmp10, tmp:tmp -> tmp11, tmp:tmp -> tmp12, class:TFun -> TFun, tmp:tmp -> tmp13, tmp:block$res -> block$res17, tmp:tmp -> tmp14, tmp:tmp -> tmp15, tmp:tmp -> tmp16, tmp:tmp -> tmp17, tmp:tmp -> tmp18, tmp:tmp -> tmp19, tmp:inlinedVal -> inlinedVal2, tmp:tmp -> tmp20, tmp:scrut -> scrut2, tmp:block$res -> block$res18, tmp:block$res -> block$res7, emptySub -> emptySub, tmp:tmp -> tmp21, tmp:tmp -> tmp22, tmp:tmp -> tmp23, tmp:tmp -> tmp, tmp:tmp -> tmp24, member:Predef -> Predef, tmp:block$res -> block$res8, tmp:block$res -> block$res19, member:applyPattern -> applyPattern, tmp:tmp -> tmp25, tmp:tmp -> tmp26, tmp:tmp -> tmp27, tmp:inlinedVal -> inlinedVal3, tmp:block$res -> block$res9, tmp:tmp -> tmp28, tmp:scrut -> scrut3, member:Unify -> Unify1, tmp:block$res -> block$res20, pattern:Unify -> Unify, member:Env -> Env1, class:Env -> Env, member:Iter -> Iter, class:TVar -> TVar, class:TPrim -> TPrim, member:Runtime -> Runtime, member:inferTop -> inferTop, tmp:block$res -> block$res5, member:Scheme -> Scheme1, class:Scheme -> Scheme, tmp:block$res -> block$res24, tmp:block$res -> block$res10, member:unify' -> unify$_, member:inferType -> inferType, tmp:block$res -> block$res3, TInt -> TInt, TBool -> TBool, tmp:block$res -> block$res4, member:Term -> Term2, member:IntLit -> IntLit1, member:Var -> Var1, member:App -> App1, tmp:block$res -> block$res11, member:Abs -> Abs1, member:BoolLit -> BoolLit1, member:unify -> unify, member:ShowTerm -> ShowTerm1, pattern:ShowTerm -> ShowTerm, class:Abs -> Abs, tmp:block$res -> block$res25, id -> id, const -> const1, class:App -> App, tmp:block$res -> block$res21, emptyEnv -> emptyEnv, apply -> apply, tmp:block$res -> block$res6, tmp:tmp -> tmp29, tmp:block$res -> block$res22, compose -> compose, member:Subst -> Subst1, class:Subst -> Subst, member:Gen -> Gen1, class:Gen -> Gen, tmp:tmp -> tmp30, tmp:tmp -> tmp31, tmp:tmp -> tmp32, tmp:tmp -> tmp33, tmp:tmp -> tmp34, tmp:tmp -> tmp35, tmp:tmp -> tmp36, tmp:tmp -> tmp37, tmp:tmp -> tmp38, tmp:tmp -> tmp39, tmp:tmp -> tmp40, class:Term -> Term1, tmp:tmp -> tmp41, tmp:tmp -> tmp42, tmp:tmp -> tmp43, tmp:block$res -> block$res26, class:Var -> Var, tmp:block$res -> block$res27, env -> env, term -> term, tmp:block$res -> block$res23, member:instance$Ident(Gen) -> instance$Ident$_Gen$_, tmp:tmp -> tmp44, class:IntLit -> IntLit, tmp:tmp -> tmp45, tmp:inlinedVal -> inlinedVal4, tmp:block$res -> block$res28, class:BoolLit -> BoolLit)
-//│     defaultImportBindings = HashMap(/storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Iter.mjs -> Iter, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Option.mjs -> Option, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Runtime.mjs -> Runtime, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Predef.mjs -> Predef)
-//│ ═══[COMPILATION ERROR] No definition found in scope for member 'infer$tailrec'
-//│ FAILURE: Unexpected runtime error
-//│ FAILURE LOCATION: mkQuery (JSBackendDiffMaker.scala:259)
-//│ ═══[RUNTIME ERROR] ReferenceError: infer$tailrec is not defined
-//│     at REPL94:1:197
-//│     at ContextifyScript.runInThisContext (node:vm:138:12)
-//│     at defaultEval (node:repl:608:24)
-//│     at REPLEvalInContext (node:repl:691:9)
-//│     at AsyncLocalStorage.run (node:internal/async_local_storage/async_context_frame:66:14)
-//│     at REPLServer.REPLEval [as eval] (node:repl:690:19)
-//│     at REPLServer.onLine (node:repl:828:12)
-//│     at REPLServer.emit (node:events:514:20)
-//│     at [_onLine] [as _onLine] (node:internal/readline/interface:474:12)
-//│     at [_normalWrite] [as _normalWrite] (node:internal/readline/interface:669:18)
+//│ = "∀t₀. t₀ -> t₀"
 
 emptyEnv |- const
-//│ FAILURE: Unexpected compilation error
-//│ FAILURE LOCATION: lookup_! (Scope.scala:136)
-//│ FAILURE INFO: Tuple2:
-//│   _1 = Tuple2:
-//│     _1 = member:infer$tailrec⁰
-//│     _2 = class hkmc2.semantics.BlockMemberSymbol
-//│   _2 = Scope:
-//│     parentOrCfg = Left of Cfg:
-//│       escapeChars = true
-//│       useSuperscripts = false
-//│       includeZero = false
-//│       defaultName = "tmp"
-//│     curThis = S of S of globalThis:globalThis⁰
-//│     bindings = HashMap(term -> term1, member:instance$Ident(Gen) -> instance$Ident$_Gen$_1, tmp:runtime -> runtime, tmp:block$res -> block$res12, tmp:tmp -> tmp46, tmp:definitionMetadata -> definitionMetadata, tmp:tmp -> tmp47, tmp:prettyPrint -> prettyPrint, tmp:inlinedVal -> inlinedVal5, tmp:Term -> Term, tmp:Block -> Block, tmp:tmp -> tmp1, tmp:block$res -> block$res29, tmp:option -> option, tmp:block$res -> block$res13, t1 -> t1, t2 -> t2, tmp:inlinedVal -> inlinedVal, tmp:tmp -> tmp2, tmp:scrut -> scrut, tmp:block$res -> block$res14, tmp:tmp -> tmp3, tmp:tmp -> tmp4, tmp:block$res -> block$res15, tmp:tmp -> tmp5, t2 -> t21, tmp:inlinedVal -> inlinedVal1, member:lambda$ -> lambda$, tmp:block$res -> block$res, tmp:tmp -> tmp6, tmp:scrut -> scrut1, tmp:block$res -> block$res1, tmp:block$res -> block$res16, tmp:block$res -> block$res2, member:Option -> Option, member:Type -> Type1, member:TVar -> TVar1, member:TFun -> TFun1, tmp:tmp -> tmp7, member:TPrim -> TPrim1, tmp:tmp -> tmp8, class:Type -> Type, tmp:tmp -> tmp9, tmp:tmp -> tmp10, tmp:tmp -> tmp11, tmp:tmp -> tmp12, class:TFun -> TFun, tmp:tmp -> tmp13, tmp:block$res -> block$res17, tmp:tmp -> tmp14, tmp:tmp -> tmp15, tmp:tmp -> tmp16, tmp:tmp -> tmp17, tmp:tmp -> tmp18, tmp:tmp -> tmp19, tmp:inlinedVal -> inlinedVal2, tmp:tmp -> tmp20, tmp:scrut -> scrut2, tmp:block$res -> block$res18, tmp:block$res -> block$res7, emptySub -> emptySub, tmp:tmp -> tmp21, tmp:tmp -> tmp22, tmp:tmp -> tmp23, tmp:tmp -> tmp, tmp:tmp -> tmp24, member:Predef -> Predef, tmp:block$res -> block$res8, tmp:block$res -> block$res19, member:applyPattern -> applyPattern, tmp:tmp -> tmp25, tmp:tmp -> tmp26, tmp:tmp -> tmp27, tmp:inlinedVal -> inlinedVal3, tmp:block$res -> block$res9, tmp:tmp -> tmp28, tmp:scrut -> scrut3, member:Unify -> Unify1, tmp:block$res -> block$res20, pattern:Unify -> Unify, member:Env -> Env1, class:Env -> Env, member:Iter -> Iter, class:TVar -> TVar, class:TPrim -> TPrim, member:Runtime -> Runtime, member:inferTop -> inferTop, tmp:block$res -> block$res5, member:Scheme -> Scheme1, class:Scheme -> Scheme, tmp:block$res -> block$res24, tmp:block$res -> block$res10, member:unify' -> unify$_, member:inferType -> inferType, tmp:block$res -> block$res3, TInt -> TInt, TBool -> TBool, tmp:block$res -> block$res4, member:Term -> Term2, member:IntLit -> IntLit1, member:Var -> Var1, member:App -> App1, tmp:block$res -> block$res11, member:Abs -> Abs1, member:BoolLit -> BoolLit1, member:unify -> unify, member:ShowTerm -> ShowTerm1, pattern:ShowTerm -> ShowTerm, class:Abs -> Abs, tmp:block$res -> block$res25, id -> id, const -> const1, class:App -> App, tmp:block$res -> block$res21, emptyEnv -> emptyEnv, apply -> apply, tmp:block$res -> block$res6, tmp:tmp -> tmp29, tmp:block$res -> block$res22, compose -> compose, member:Subst -> Subst1, class:Subst -> Subst, member:Gen -> Gen1, class:Gen -> Gen, tmp:tmp -> tmp30, tmp:tmp -> tmp31, tmp:tmp -> tmp32, tmp:tmp -> tmp33, tmp:tmp -> tmp34, tmp:tmp -> tmp35, tmp:tmp -> tmp36, tmp:tmp -> tmp37, tmp:tmp -> tmp38, tmp:tmp -> tmp39, tmp:tmp -> tmp40, class:Term -> Term1, tmp:tmp -> tmp41, tmp:tmp -> tmp42, tmp:tmp -> tmp43, tmp:block$res -> block$res26, class:Var -> Var, tmp:block$res -> block$res27, env -> env, term -> term, tmp:block$res -> block$res23, member:instance$Ident(Gen) -> instance$Ident$_Gen$_, tmp:tmp -> tmp44, class:IntLit -> IntLit, tmp:tmp -> tmp45, tmp:inlinedVal -> inlinedVal4, tmp:block$res -> block$res28, class:BoolLit -> BoolLit, env -> env1)
-//│     defaultImportBindings = HashMap(/storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Iter.mjs -> Iter, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Option.mjs -> Option, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Runtime.mjs -> Runtime, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Predef.mjs -> Predef)
-//│ ═══[COMPILATION ERROR] No definition found in scope for member 'infer$tailrec'
-//│ FAILURE: Unexpected runtime error
-//│ FAILURE LOCATION: mkQuery (JSBackendDiffMaker.scala:259)
-//│ ═══[RUNTIME ERROR] ReferenceError: infer$tailrec is not defined
-//│     at REPL97:1:207
-//│     at ContextifyScript.runInThisContext (node:vm:138:12)
-//│     at defaultEval (node:repl:608:24)
-//│     at REPLEvalInContext (node:repl:691:9)
-//│     at AsyncLocalStorage.run (node:internal/async_local_storage/async_context_frame:66:14)
-//│     at REPLServer.REPLEval [as eval] (node:repl:690:19)
-//│     at REPLServer.onLine (node:repl:828:12)
-//│     at REPLServer.emit (node:events:514:20)
-//│     at [_onLine] [as _onLine] (node:internal/readline/interface:474:12)
-//│     at [_normalWrite] [as _normalWrite] (node:internal/readline/interface:669:18)
+//│ = "∀t₀, t₁. t₀ -> t₁ -> t₀"
 
 emptyEnv |- apply
-//│ FAILURE: Unexpected compilation error
-//│ FAILURE LOCATION: lookup_! (Scope.scala:136)
-//│ FAILURE INFO: Tuple2:
-//│   _1 = Tuple2:
-//│     _1 = member:infer$tailrec⁰
-//│     _2 = class hkmc2.semantics.BlockMemberSymbol
-//│   _2 = Scope:
-//│     parentOrCfg = Left of Cfg:
-//│       escapeChars = true
-//│       useSuperscripts = false
-//│       includeZero = false
-//│       defaultName = "tmp"
-//│     curThis = S of S of globalThis:globalThis⁰
-//│     bindings = HashMap(term -> term1, member:instance$Ident(Gen) -> instance$Ident$_Gen$_1, tmp:runtime -> runtime, tmp:block$res -> block$res12, tmp:tmp -> tmp46, tmp:definitionMetadata -> definitionMetadata, tmp:tmp -> tmp47, tmp:prettyPrint -> prettyPrint, tmp:inlinedVal -> inlinedVal5, tmp:Term -> Term, tmp:Block -> Block, tmp:tmp -> tmp1, tmp:block$res -> block$res29, tmp:option -> option, tmp:block$res -> block$res13, env -> env2, term -> term2, t1 -> t1, t2 -> t2, member:instance$Ident(Gen) -> instance$Ident$_Gen$_2, tmp:inlinedVal -> inlinedVal, tmp:tmp -> tmp48, tmp:tmp -> tmp49, tmp:tmp -> tmp2, tmp:inlinedVal -> inlinedVal6, tmp:scrut -> scrut, tmp:block$res -> block$res14, tmp:block$res -> block$res30, tmp:tmp -> tmp3, tmp:tmp -> tmp4, tmp:block$res -> block$res15, tmp:tmp -> tmp5, t2 -> t21, tmp:inlinedVal -> inlinedVal1, member:lambda$ -> lambda$, tmp:block$res -> block$res, tmp:tmp -> tmp6, tmp:scrut -> scrut1, tmp:block$res -> block$res1, tmp:block$res -> block$res16, tmp:block$res -> block$res2, member:Option -> Option, member:Type -> Type1, member:TVar -> TVar1, member:TFun -> TFun1, tmp:tmp -> tmp7, member:TPrim -> TPrim1, tmp:tmp -> tmp8, class:Type -> Type, tmp:tmp -> tmp9, tmp:tmp -> tmp10, tmp:tmp -> tmp11, tmp:tmp -> tmp12, class:TFun -> TFun, tmp:tmp -> tmp13, tmp:block$res -> block$res17, tmp:tmp -> tmp14, tmp:tmp -> tmp15, tmp:tmp -> tmp16, tmp:tmp -> tmp17, tmp:tmp -> tmp18, tmp:tmp -> tmp19, tmp:inlinedVal -> inlinedVal2, tmp:tmp -> tmp20, tmp:scrut -> scrut2, tmp:block$res -> block$res18, tmp:block$res -> block$res7, emptySub -> emptySub, tmp:tmp -> tmp21, tmp:tmp -> tmp22, tmp:tmp -> tmp23, tmp:tmp -> tmp, tmp:tmp -> tmp24, member:Predef -> Predef, tmp:block$res -> block$res8, tmp:block$res -> block$res19, member:applyPattern -> applyPattern, tmp:tmp -> tmp25, tmp:tmp -> tmp26, tmp:tmp -> tmp27, tmp:inlinedVal -> inlinedVal3, tmp:block$res -> block$res9, tmp:tmp -> tmp28, tmp:scrut -> scrut3, member:Unify -> Unify1, tmp:block$res -> block$res20, pattern:Unify -> Unify, member:Env -> Env1, class:Env -> Env, member:Iter -> Iter, class:TVar -> TVar, class:TPrim -> TPrim, member:Runtime -> Runtime, member:inferTop -> inferTop, tmp:block$res -> block$res5, member:Scheme -> Scheme1, class:Scheme -> Scheme, tmp:block$res -> block$res24, tmp:block$res -> block$res10, member:unify' -> unify$_, member:inferType -> inferType, tmp:block$res -> block$res3, TInt -> TInt, TBool -> TBool, tmp:block$res -> block$res4, member:Term -> Term2, member:IntLit -> IntLit1, member:Var -> Var1, member:App -> App1, tmp:block$res -> block$res11, member:Abs -> Abs1, member:BoolLit -> BoolLit1, member:unify -> unify, member:ShowTerm -> ShowTerm1, pattern:ShowTerm -> ShowTerm, class:Abs -> Abs, tmp:block$res -> block$res25, id -> id, const -> const1, class:App -> App, tmp:block$res -> block$res21, emptyEnv -> emptyEnv, apply -> apply, tmp:block$res -> block$res6, tmp:tmp -> tmp29, tmp:block$res -> block$res22, compose -> compose, member:Subst -> Subst1, class:Subst -> Subst, member:Gen -> Gen1, class:Gen -> Gen, tmp:tmp -> tmp30, tmp:tmp -> tmp31, tmp:tmp -> tmp32, tmp:tmp -> tmp33, tmp:tmp -> tmp34, tmp:tmp -> tmp35, tmp:tmp -> tmp36, tmp:tmp -> tmp37, tmp:tmp -> tmp38, tmp:tmp -> tmp39, tmp:tmp -> tmp40, class:Term -> Term1, tmp:tmp -> tmp41, tmp:tmp -> tmp42, tmp:tmp -> tmp43, tmp:block$res -> block$res26, class:Var -> Var, tmp:block$res -> block$res27, env -> env, term -> term, tmp:block$res -> block$res23, member:instance$Ident(Gen) -> instance$Ident$_Gen$_, tmp:tmp -> tmp44, class:IntLit -> IntLit, tmp:tmp -> tmp45, tmp:inlinedVal -> inlinedVal4, tmp:block$res -> block$res28, class:BoolLit -> BoolLit, env -> env1)
-//│     defaultImportBindings = HashMap(/storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Iter.mjs -> Iter, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Option.mjs -> Option, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Runtime.mjs -> Runtime, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Predef.mjs -> Predef)
-//│ ═══[COMPILATION ERROR] No definition found in scope for member 'infer$tailrec'
-//│ FAILURE: Unexpected runtime error
-//│ FAILURE LOCATION: mkQuery (JSBackendDiffMaker.scala:259)
-//│ ═══[RUNTIME ERROR] ReferenceError: infer$tailrec is not defined
-//│     at REPL100:1:206
-//│     at ContextifyScript.runInThisContext (node:vm:138:12)
-//│     at defaultEval (node:repl:608:24)
-//│     at REPLEvalInContext (node:repl:691:9)
-//│     at AsyncLocalStorage.run (node:internal/async_local_storage/async_context_frame:66:14)
-//│     at REPLServer.REPLEval [as eval] (node:repl:690:19)
-//│     at REPLServer.onLine (node:repl:828:12)
-//│     at REPLServer.emit (node:events:514:20)
-//│     at [_onLine] [as _onLine] (node:internal/readline/interface:474:12)
-//│     at [_normalWrite] [as _normalWrite] (node:internal/readline/interface:669:18)
+//│ = "∀t₁, t₂. (t₁ -> t₂) -> t₁ -> t₂"
 
 emptyEnv |- compose
-//│ FAILURE: Unexpected compilation error
-//│ FAILURE LOCATION: lookup_! (Scope.scala:136)
-//│ FAILURE INFO: Tuple2:
-//│   _1 = Tuple2:
-//│     _1 = member:infer$tailrec⁰
-//│     _2 = class hkmc2.semantics.BlockMemberSymbol
-//│   _2 = Scope:
-//│     parentOrCfg = Left of Cfg:
-//│       escapeChars = true
-//│       useSuperscripts = false
-//│       includeZero = false
-//│       defaultName = "tmp"
-//│     curThis = S of S of globalThis:globalThis⁰
-//│     bindings = HashMap(term -> term1, member:instance$Ident(Gen) -> instance$Ident$_Gen$_1, tmp:runtime -> runtime, tmp:block$res -> block$res12, tmp:tmp -> tmp46, tmp:definitionMetadata -> definitionMetadata, tmp:tmp -> tmp47, tmp:prettyPrint -> prettyPrint, tmp:inlinedVal -> inlinedVal5, tmp:Term -> Term, tmp:Block -> Block, tmp:tmp -> tmp1, tmp:block$res -> block$res29, tmp:option -> option, tmp:block$res -> block$res13, env -> env2, term -> term2, t1 -> t1, t2 -> t2, member:instance$Ident(Gen) -> instance$Ident$_Gen$_2, tmp:inlinedVal -> inlinedVal, tmp:tmp -> tmp48, tmp:tmp -> tmp49, tmp:tmp -> tmp2, tmp:inlinedVal -> inlinedVal6, tmp:scrut -> scrut, tmp:block$res -> block$res14, tmp:block$res -> block$res30, env -> env3, term -> term3, tmp:tmp -> tmp3, tmp:tmp -> tmp4, tmp:block$res -> block$res15, member:instance$Ident(Gen) -> instance$Ident$_Gen$_3, tmp:tmp -> tmp50, tmp:tmp -> tmp51, tmp:inlinedVal -> inlinedVal7, tmp:tmp -> tmp5, tmp:block$res -> block$res31, t2 -> t21, tmp:inlinedVal -> inlinedVal1, member:lambda$ -> lambda$, tmp:block$res -> block$res, tmp:tmp -> tmp6, tmp:scrut -> scrut1, tmp:block$res -> block$res1, tmp:block$res -> block$res16, tmp:block$res -> block$res2, member:Option -> Option, member:Type -> Type1, member:TVar -> TVar1, member:TFun -> TFun1, tmp:tmp -> tmp7, member:TPrim -> TPrim1, tmp:tmp -> tmp8, class:Type -> Type, tmp:tmp -> tmp9, tmp:tmp -> tmp10, tmp:tmp -> tmp11, tmp:tmp -> tmp12, class:TFun -> TFun, tmp:tmp -> tmp13, tmp:block$res -> block$res17, tmp:tmp -> tmp14, tmp:tmp -> tmp15, tmp:tmp -> tmp16, tmp:tmp -> tmp17, tmp:tmp -> tmp18, tmp:tmp -> tmp19, tmp:inlinedVal -> inlinedVal2, tmp:tmp -> tmp20, tmp:scrut -> scrut2, tmp:block$res -> block$res18, tmp:block$res -> block$res7, emptySub -> emptySub, tmp:tmp -> tmp21, tmp:tmp -> tmp22, tmp:tmp -> tmp23, tmp:tmp -> tmp, tmp:tmp -> tmp24, member:Predef -> Predef, tmp:block$res -> block$res8, tmp:block$res -> block$res19, member:applyPattern -> applyPattern, tmp:tmp -> tmp25, tmp:tmp -> tmp26, tmp:tmp -> tmp27, tmp:inlinedVal -> inlinedVal3, tmp:block$res -> block$res9, tmp:tmp -> tmp28, tmp:scrut -> scrut3, member:Unify -> Unify1, tmp:block$res -> block$res20, pattern:Unify -> Unify, member:Env -> Env1, class:Env -> Env, member:Iter -> Iter, class:TVar -> TVar, class:TPrim -> TPrim, member:Runtime -> Runtime, member:inferTop -> inferTop, tmp:block$res -> block$res5, member:Scheme -> Scheme1, class:Scheme -> Scheme, tmp:block$res -> block$res24, tmp:block$res -> block$res10, member:unify' -> unify$_, member:inferType -> inferType, tmp:block$res -> block$res3, TInt -> TInt, TBool -> TBool, tmp:block$res -> block$res4, member:Term -> Term2, member:IntLit -> IntLit1, member:Var -> Var1, member:App -> App1, tmp:block$res -> block$res11, member:Abs -> Abs1, member:BoolLit -> BoolLit1, member:unify -> unify, member:ShowTerm -> ShowTerm1, pattern:ShowTerm -> ShowTerm, class:Abs -> Abs, tmp:block$res -> block$res25, id -> id, const -> const1, class:App -> App, tmp:block$res -> block$res21, emptyEnv -> emptyEnv, apply -> apply, tmp:block$res -> block$res6, tmp:tmp -> tmp29, tmp:block$res -> block$res22, compose -> compose, member:Subst -> Subst1, class:Subst -> Subst, member:Gen -> Gen1, class:Gen -> Gen, tmp:tmp -> tmp30, tmp:tmp -> tmp31, tmp:tmp -> tmp32, tmp:tmp -> tmp33, tmp:tmp -> tmp34, tmp:tmp -> tmp35, tmp:tmp -> tmp36, tmp:tmp -> tmp37, tmp:tmp -> tmp38, tmp:tmp -> tmp39, tmp:tmp -> tmp40, class:Term -> Term1, tmp:tmp -> tmp41, tmp:tmp -> tmp42, tmp:tmp -> tmp43, tmp:block$res -> block$res26, class:Var -> Var, tmp:block$res -> block$res27, env -> env, term -> term, tmp:block$res -> block$res23, member:instance$Ident(Gen) -> instance$Ident$_Gen$_, tmp:tmp -> tmp44, class:IntLit -> IntLit, tmp:tmp -> tmp45, tmp:inlinedVal -> inlinedVal4, tmp:block$res -> block$res28, class:BoolLit -> BoolLit, env -> env1)
-//│     defaultImportBindings = HashMap(/storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Iter.mjs -> Iter, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Option.mjs -> Option, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Runtime.mjs -> Runtime, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Predef.mjs -> Predef)
-//│ ═══[COMPILATION ERROR] No definition found in scope for member 'infer$tailrec'
-//│ FAILURE: Unexpected runtime error
-//│ FAILURE LOCATION: mkQuery (JSBackendDiffMaker.scala:259)
-//│ ═══[RUNTIME ERROR] ReferenceError: infer$tailrec is not defined
-//│     at REPL103:1:208
-//│     at ContextifyScript.runInThisContext (node:vm:138:12)
-//│     at defaultEval (node:repl:608:24)
-//│     at REPLEvalInContext (node:repl:691:9)
-//│     at AsyncLocalStorage.run (node:internal/async_local_storage/async_context_frame:66:14)
-//│     at REPLServer.REPLEval [as eval] (node:repl:690:19)
-//│     at REPLServer.onLine (node:repl:828:12)
-//│     at REPLServer.emit (node:events:514:20)
-//│     at [_onLine] [as _onLine] (node:internal/readline/interface:474:12)
-//│     at [_normalWrite] [as _normalWrite] (node:internal/readline/interface:669:18)
+//│ = "∀t₃, t₄, t₂. (t₃ -> t₄) -> (t₂ -> t₃) -> t₂ -> t₄"
 
 :expect "Int"
 emptyEnv |- IntLit(42)
-//│ FAILURE: Unexpected compilation error
-//│ FAILURE LOCATION: lookup_! (Scope.scala:136)
-//│ FAILURE INFO: Tuple2:
-//│   _1 = Tuple2:
-//│     _1 = member:infer$tailrec⁰
-//│     _2 = class hkmc2.semantics.BlockMemberSymbol
-//│   _2 = Scope:
-//│     parentOrCfg = Left of Cfg:
-//│       escapeChars = true
-//│       useSuperscripts = false
-//│       includeZero = false
-//│       defaultName = "tmp"
-//│     curThis = S of S of globalThis:globalThis⁰
-//│     bindings = HashMap(term -> term1, member:instance$Ident(Gen) -> instance$Ident$_Gen$_1, tmp:runtime -> runtime, tmp:block$res -> block$res12, tmp:tmp -> tmp46, tmp:definitionMetadata -> definitionMetadata, tmp:tmp -> tmp47, tmp:prettyPrint -> prettyPrint, tmp:inlinedVal -> inlinedVal5, tmp:Term -> Term, tmp:Block -> Block, tmp:tmp -> tmp1, tmp:block$res -> block$res29, tmp:option -> option, tmp:block$res -> block$res13, env -> env2, term -> term2, t1 -> t1, t2 -> t2, member:instance$Ident(Gen) -> instance$Ident$_Gen$_2, tmp:inlinedVal -> inlinedVal, tmp:tmp -> tmp48, tmp:tmp -> tmp49, tmp:tmp -> tmp2, tmp:inlinedVal -> inlinedVal6, tmp:scrut -> scrut, tmp:block$res -> block$res14, tmp:block$res -> block$res30, env -> env3, term -> term3, tmp:tmp -> tmp3, tmp:tmp -> tmp4, tmp:block$res -> block$res15, member:instance$Ident(Gen) -> instance$Ident$_Gen$_3, tmp:tmp -> tmp50, tmp:tmp -> tmp51, tmp:inlinedVal -> inlinedVal7, tmp:tmp -> tmp5, tmp:block$res -> block$res31, t2 -> t21, tmp:inlinedVal -> inlinedVal1, member:lambda$ -> lambda$, tmp:tmp -> tmp52, env -> env4, tmp:block$res -> block$res, tmp:tmp -> tmp6, tmp:scrut -> scrut1, tmp:block$res -> block$res1, tmp:block$res -> block$res16, member:instance$Ident(Gen) -> instance$Ident$_Gen$_4, tmp:block$res -> block$res2, tmp:tmp -> tmp53, tmp:tmp -> tmp54, tmp:inlinedVal -> inlinedVal8, member:Option -> Option, tmp:block$res -> block$res32, member:Type -> Type1, member:TVar -> TVar1, member:TFun -> TFun1, tmp:tmp -> tmp7, member:TPrim -> TPrim1, tmp:tmp -> tmp8, class:Type -> Type, tmp:tmp -> tmp9, tmp:tmp -> tmp10, tmp:tmp -> tmp11, tmp:tmp -> tmp12, class:TFun -> TFun, tmp:tmp -> tmp13, tmp:block$res -> block$res17, tmp:tmp -> tmp14, tmp:tmp -> tmp15, tmp:tmp -> tmp16, tmp:tmp -> tmp17, tmp:tmp -> tmp18, tmp:tmp -> tmp19, tmp:inlinedVal -> inlinedVal2, tmp:tmp -> tmp20, tmp:scrut -> scrut2, tmp:block$res -> block$res18, tmp:block$res -> block$res7, emptySub -> emptySub, tmp:tmp -> tmp21, tmp:tmp -> tmp22, tmp:tmp -> tmp23, tmp:tmp -> tmp, tmp:tmp -> tmp24, member:Predef -> Predef, tmp:block$res -> block$res8, tmp:block$res -> block$res19, member:applyPattern -> applyPattern, tmp:tmp -> tmp25, tmp:tmp -> tmp26, tmp:tmp -> tmp27, tmp:inlinedVal -> inlinedVal3, tmp:block$res -> block$res9, tmp:tmp -> tmp28, tmp:scrut -> scrut3, member:Unify -> Unify1, tmp:block$res -> block$res20, pattern:Unify -> Unify, member:Env -> Env1, class:Env -> Env, member:Iter -> Iter, class:TVar -> TVar, class:TPrim -> TPrim, member:Runtime -> Runtime, member:inferTop -> inferTop, tmp:block$res -> block$res5, member:Scheme -> Scheme1, class:Scheme -> Scheme, tmp:block$res -> block$res24, tmp:block$res -> block$res10, member:unify' -> unify$_, member:inferType -> inferType, tmp:block$res -> block$res3, TInt -> TInt, TBool -> TBool, tmp:block$res -> block$res4, member:Term -> Term2, member:IntLit -> IntLit1, member:Var -> Var1, member:App -> App1, tmp:block$res -> block$res11, member:Abs -> Abs1, member:BoolLit -> BoolLit1, member:unify -> unify, member:ShowTerm -> ShowTerm1, pattern:ShowTerm -> ShowTerm, class:Abs -> Abs, tmp:block$res -> block$res25, id -> id, const -> const1, class:App -> App, tmp:block$res -> block$res21, emptyEnv -> emptyEnv, apply -> apply, tmp:block$res -> block$res6, tmp:tmp -> tmp29, tmp:block$res -> block$res22, compose -> compose, member:Subst -> Subst1, class:Subst -> Subst, member:Gen -> Gen1, class:Gen -> Gen, tmp:tmp -> tmp30, tmp:tmp -> tmp31, tmp:tmp -> tmp32, tmp:tmp -> tmp33, tmp:tmp -> tmp34, tmp:tmp -> tmp35, tmp:tmp -> tmp36, tmp:tmp -> tmp37, tmp:tmp -> tmp38, tmp:tmp -> tmp39, tmp:tmp -> tmp40, class:Term -> Term1, tmp:tmp -> tmp41, tmp:tmp -> tmp42, tmp:tmp -> tmp43, tmp:block$res -> block$res26, class:Var -> Var, tmp:block$res -> block$res27, env -> env, term -> term, tmp:block$res -> block$res23, member:instance$Ident(Gen) -> instance$Ident$_Gen$_, tmp:tmp -> tmp44, class:IntLit -> IntLit, tmp:tmp -> tmp45, tmp:inlinedVal -> inlinedVal4, tmp:block$res -> block$res28, class:BoolLit -> BoolLit, env -> env1)
-//│     defaultImportBindings = HashMap(/storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Iter.mjs -> Iter, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Option.mjs -> Option, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Runtime.mjs -> Runtime, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Predef.mjs -> Predef)
-//│ ═══[COMPILATION ERROR] No definition found in scope for member 'infer$tailrec'
-//│ FAILURE: Unexpected runtime error
-//│ FAILURE LOCATION: mkQuery (JSBackendDiffMaker.scala:259)
-//│ ═══[RUNTIME ERROR] ReferenceError: infer$tailrec is not defined
-//│     at REPL106:1:231
-//│     at ContextifyScript.runInThisContext (node:vm:138:12)
-//│     at defaultEval (node:repl:608:24)
-//│     at REPLEvalInContext (node:repl:691:9)
-//│     at AsyncLocalStorage.run (node:internal/async_local_storage/async_context_frame:66:14)
-//│     at REPLServer.REPLEval [as eval] (node:repl:690:19)
-//│     at REPLServer.onLine (node:repl:828:12)
-//│     at REPLServer.emit (node:events:514:20)
-//│     at [_onLine] [as _onLine] (node:internal/readline/interface:474:12)
-//│     at [_normalWrite] [as _normalWrite] (node:internal/readline/interface:669:18)
-//│ FAILURE: Unexpected runtime error
-//│ FAILURE LOCATION: processIRBlock (JSBackendDiffMaker.scala:299)
-//│ ═══[RUNTIME ERROR] Expected: '"Int"', got: 'undefined'
+//│ = "Int"
 
 :expect "Bool"
 emptyEnv |- BoolLit(true)
-//│ FAILURE: Unexpected compilation error
-//│ FAILURE LOCATION: lookup_! (Scope.scala:136)
-//│ FAILURE INFO: Tuple2:
-//│   _1 = Tuple2:
-//│     _1 = member:infer$tailrec⁰
-//│     _2 = class hkmc2.semantics.BlockMemberSymbol
-//│   _2 = Scope:
-//│     parentOrCfg = Left of Cfg:
-//│       escapeChars = true
-//│       useSuperscripts = false
-//│       includeZero = false
-//│       defaultName = "tmp"
-//│     curThis = S of S of globalThis:globalThis⁰
-//│     bindings = HashMap(term -> term1, member:instance$Ident(Gen) -> instance$Ident$_Gen$_1, tmp:runtime -> runtime, tmp:block$res -> block$res12, tmp:tmp -> tmp46, tmp:definitionMetadata -> definitionMetadata, tmp:tmp -> tmp47, tmp:prettyPrint -> prettyPrint, tmp:inlinedVal -> inlinedVal5, tmp:Term -> Term, tmp:Block -> Block, tmp:tmp -> tmp1, tmp:block$res -> block$res29, tmp:option -> option, tmp:block$res -> block$res13, env -> env2, term -> term2, t1 -> t1, t2 -> t2, member:instance$Ident(Gen) -> instance$Ident$_Gen$_2, tmp:inlinedVal -> inlinedVal, tmp:tmp -> tmp48, tmp:tmp -> tmp49, tmp:tmp -> tmp2, tmp:inlinedVal -> inlinedVal6, tmp:scrut -> scrut, tmp:block$res -> block$res14, tmp:block$res -> block$res30, env -> env3, term -> term3, tmp:tmp -> tmp3, tmp:tmp -> tmp4, tmp:block$res -> block$res15, member:instance$Ident(Gen) -> instance$Ident$_Gen$_3, tmp:tmp -> tmp50, tmp:tmp -> tmp51, tmp:inlinedVal -> inlinedVal7, tmp:tmp -> tmp5, tmp:block$res -> block$res31, t2 -> t21, tmp:inlinedVal -> inlinedVal1, member:lambda$ -> lambda$, tmp:tmp -> tmp52, env -> env4, tmp:block$res -> block$res, tmp:tmp -> tmp6, tmp:scrut -> scrut1, tmp:block$res -> block$res1, tmp:block$res -> block$res16, member:instance$Ident(Gen) -> instance$Ident$_Gen$_4, tmp:block$res -> block$res2, tmp:tmp -> tmp53, tmp:tmp -> tmp54, tmp:inlinedVal -> inlinedVal8, member:Option -> Option, tmp:block$res -> block$res32, member:Type -> Type1, member:TVar -> TVar1, member:TFun -> TFun1, tmp:tmp -> tmp7, tmp:tmp -> tmp55, member:TPrim -> TPrim1, tmp:tmp -> tmp8, env -> env5, class:Type -> Type, tmp:tmp -> tmp9, tmp:tmp -> tmp10, tmp:tmp -> tmp11, tmp:tmp -> tmp12, member:instance$Ident(Gen) -> instance$Ident$_Gen$_5, class:TFun -> TFun, tmp:tmp -> tmp13, tmp:tmp -> tmp56, tmp:block$res -> block$res17, tmp:tmp -> tmp57, tmp:inlinedVal -> inlinedVal9, tmp:block$res -> block$res33, tmp:tmp -> tmp14, tmp:tmp -> tmp15, tmp:tmp -> tmp16, tmp:tmp -> tmp17, tmp:tmp -> tmp18, tmp:tmp -> tmp19, tmp:inlinedVal -> inlinedVal2, tmp:tmp -> tmp20, tmp:scrut -> scrut2, tmp:block$res -> block$res18, tmp:block$res -> block$res7, emptySub -> emptySub, tmp:tmp -> tmp21, tmp:tmp -> tmp22, tmp:tmp -> tmp23, tmp:tmp -> tmp, tmp:tmp -> tmp24, member:Predef -> Predef, tmp:block$res -> block$res8, tmp:block$res -> block$res19, member:applyPattern -> applyPattern, tmp:tmp -> tmp25, tmp:tmp -> tmp26, tmp:tmp -> tmp27, tmp:inlinedVal -> inlinedVal3, tmp:block$res -> block$res9, tmp:tmp -> tmp28, tmp:scrut -> scrut3, member:Unify -> Unify1, tmp:block$res -> block$res20, pattern:Unify -> Unify, member:Env -> Env1, class:Env -> Env, member:Iter -> Iter, class:TVar -> TVar, class:TPrim -> TPrim, member:Runtime -> Runtime, member:inferTop -> inferTop, tmp:block$res -> block$res5, member:Scheme -> Scheme1, class:Scheme -> Scheme, tmp:block$res -> block$res24, tmp:block$res -> block$res10, member:unify' -> unify$_, member:inferType -> inferType, tmp:block$res -> block$res3, TInt -> TInt, TBool -> TBool, tmp:block$res -> block$res4, member:Term -> Term2, member:IntLit -> IntLit1, member:Var -> Var1, member:App -> App1, tmp:block$res -> block$res11, member:Abs -> Abs1, member:BoolLit -> BoolLit1, member:unify -> unify, member:ShowTerm -> ShowTerm1, pattern:ShowTerm -> ShowTerm, class:Abs -> Abs, tmp:block$res -> block$res25, id -> id, const -> const1, class:App -> App, tmp:block$res -> block$res21, emptyEnv -> emptyEnv, apply -> apply, tmp:block$res -> block$res6, tmp:tmp -> tmp29, tmp:block$res -> block$res22, compose -> compose, member:Subst -> Subst1, class:Subst -> Subst, member:Gen -> Gen1, class:Gen -> Gen, tmp:tmp -> tmp30, tmp:tmp -> tmp31, tmp:tmp -> tmp32, tmp:tmp -> tmp33, tmp:tmp -> tmp34, tmp:tmp -> tmp35, tmp:tmp -> tmp36, tmp:tmp -> tmp37, tmp:tmp -> tmp38, tmp:tmp -> tmp39, tmp:tmp -> tmp40, class:Term -> Term1, tmp:tmp -> tmp41, tmp:tmp -> tmp42, tmp:tmp -> tmp43, tmp:block$res -> block$res26, class:Var -> Var, tmp:block$res -> block$res27, env -> env, term -> term, tmp:block$res -> block$res23, member:instance$Ident(Gen) -> instance$Ident$_Gen$_, tmp:tmp -> tmp44, class:IntLit -> IntLit, tmp:tmp -> tmp45, tmp:inlinedVal -> inlinedVal4, tmp:block$res -> block$res28, class:BoolLit -> BoolLit, env -> env1)
-//│     defaultImportBindings = HashMap(/storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Iter.mjs -> Iter, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Option.mjs -> Option, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Runtime.mjs -> Runtime, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Predef.mjs -> Predef)
-//│ ═══[COMPILATION ERROR] No definition found in scope for member 'infer$tailrec'
-//│ FAILURE: Unexpected runtime error
-//│ FAILURE LOCATION: mkQuery (JSBackendDiffMaker.scala:259)
-//│ ═══[RUNTIME ERROR] ReferenceError: infer$tailrec is not defined
-//│     at REPL109:1:234
-//│     at ContextifyScript.runInThisContext (node:vm:138:12)
-//│     at defaultEval (node:repl:608:24)
-//│     at REPLEvalInContext (node:repl:691:9)
-//│     at AsyncLocalStorage.run (node:internal/async_local_storage/async_context_frame:66:14)
-//│     at REPLServer.REPLEval [as eval] (node:repl:690:19)
-//│     at REPLServer.onLine (node:repl:828:12)
-//│     at REPLServer.emit (node:events:514:20)
-//│     at [_onLine] [as _onLine] (node:internal/readline/interface:474:12)
-//│     at [_normalWrite] [as _normalWrite] (node:internal/readline/interface:669:18)
-//│ FAILURE: Unexpected runtime error
-//│ FAILURE LOCATION: processIRBlock (JSBackendDiffMaker.scala:299)
-//│ ═══[RUNTIME ERROR] Expected: '"Bool"', got: 'undefined'
+//│ = "Bool"
 
 :expect "Int"
 emptyEnv |- App(id, IntLit(5))
-//│ FAILURE: Unexpected compilation error
-//│ FAILURE LOCATION: lookup_! (Scope.scala:136)
-//│ FAILURE INFO: Tuple2:
-//│   _1 = Tuple2:
-//│     _1 = member:infer$tailrec⁰
-//│     _2 = class hkmc2.semantics.BlockMemberSymbol
-//│   _2 = Scope:
-//│     parentOrCfg = Left of Cfg:
-//│       escapeChars = true
-//│       useSuperscripts = false
-//│       includeZero = false
-//│       defaultName = "tmp"
-//│     curThis = S of S of globalThis:globalThis⁰
-//│     bindings = HashMap(term -> term1, member:instance$Ident(Gen) -> instance$Ident$_Gen$_1, tmp:runtime -> runtime, tmp:block$res -> block$res12, tmp:tmp -> tmp46, tmp:definitionMetadata -> definitionMetadata, tmp:tmp -> tmp47, tmp:prettyPrint -> prettyPrint, tmp:inlinedVal -> inlinedVal5, tmp:Term -> Term, tmp:Block -> Block, tmp:tmp -> tmp1, tmp:block$res -> block$res29, tmp:option -> option, tmp:block$res -> block$res13, env -> env2, term -> term2, t1 -> t1, t2 -> t2, member:instance$Ident(Gen) -> instance$Ident$_Gen$_2, tmp:inlinedVal -> inlinedVal, tmp:tmp -> tmp48, tmp:tmp -> tmp49, tmp:tmp -> tmp2, tmp:inlinedVal -> inlinedVal6, tmp:scrut -> scrut, tmp:block$res -> block$res14, tmp:block$res -> block$res30, env -> env3, term -> term3, tmp:tmp -> tmp3, tmp:tmp -> tmp4, tmp:block$res -> block$res15, member:instance$Ident(Gen) -> instance$Ident$_Gen$_3, tmp:tmp -> tmp50, tmp:tmp -> tmp51, tmp:inlinedVal -> inlinedVal7, tmp:tmp -> tmp5, tmp:block$res -> block$res31, t2 -> t21, tmp:inlinedVal -> inlinedVal1, member:lambda$ -> lambda$, tmp:tmp -> tmp52, env -> env4, tmp:block$res -> block$res, tmp:tmp -> tmp6, tmp:scrut -> scrut1, tmp:block$res -> block$res1, tmp:block$res -> block$res16, member:instance$Ident(Gen) -> instance$Ident$_Gen$_4, tmp:block$res -> block$res2, tmp:tmp -> tmp53, tmp:tmp -> tmp54, tmp:inlinedVal -> inlinedVal8, member:Option -> Option, tmp:block$res -> block$res32, member:Type -> Type1, member:TVar -> TVar1, member:TFun -> TFun1, tmp:tmp -> tmp7, tmp:tmp -> tmp55, member:TPrim -> TPrim1, tmp:tmp -> tmp8, env -> env5, class:Type -> Type, tmp:tmp -> tmp9, tmp:tmp -> tmp10, tmp:tmp -> tmp11, tmp:tmp -> tmp12, member:instance$Ident(Gen) -> instance$Ident$_Gen$_5, class:TFun -> TFun, tmp:tmp -> tmp13, tmp:tmp -> tmp56, tmp:block$res -> block$res17, tmp:tmp -> tmp57, tmp:inlinedVal -> inlinedVal9, tmp:block$res -> block$res33, tmp:tmp -> tmp58, tmp:tmp -> tmp59, tmp:tmp -> tmp14, env -> env6, tmp:tmp -> tmp15, tmp:tmp -> tmp16, tmp:tmp -> tmp17, tmp:tmp -> tmp18, member:instance$Ident(Gen) -> instance$Ident$_Gen$_6, tmp:tmp -> tmp19, tmp:tmp -> tmp60, tmp:tmp -> tmp61, tmp:inlinedVal -> inlinedVal10, tmp:inlinedVal -> inlinedVal2, tmp:block$res -> block$res34, tmp:tmp -> tmp20, tmp:scrut -> scrut2, tmp:block$res -> block$res18, tmp:block$res -> block$res7, emptySub -> emptySub, tmp:tmp -> tmp21, tmp:tmp -> tmp22, tmp:tmp -> tmp23, tmp:tmp -> tmp, tmp:tmp -> tmp24, member:Predef -> Predef, tmp:block$res -> block$res8, tmp:block$res -> block$res19, member:applyPattern -> applyPattern, tmp:tmp -> tmp25, tmp:tmp -> tmp26, tmp:tmp -> tmp27, tmp:inlinedVal -> inlinedVal3, tmp:block$res -> block$res9, tmp:tmp -> tmp28, tmp:scrut -> scrut3, member:Unify -> Unify1, tmp:block$res -> block$res20, pattern:Unify -> Unify, member:Env -> Env1, class:Env -> Env, member:Iter -> Iter, class:TVar -> TVar, class:TPrim -> TPrim, member:Runtime -> Runtime, member:inferTop -> inferTop, tmp:block$res -> block$res5, member:Scheme -> Scheme1, class:Scheme -> Scheme, tmp:block$res -> block$res24, tmp:block$res -> block$res10, member:unify' -> unify$_, member:inferType -> inferType, tmp:block$res -> block$res3, TInt -> TInt, TBool -> TBool, tmp:block$res -> block$res4, member:Term -> Term2, member:IntLit -> IntLit1, member:Var -> Var1, member:App -> App1, tmp:block$res -> block$res11, member:Abs -> Abs1, member:BoolLit -> BoolLit1, member:unify -> unify, member:ShowTerm -> ShowTerm1, pattern:ShowTerm -> ShowTerm, class:Abs -> Abs, tmp:block$res -> block$res25, id -> id, const -> const1, class:App -> App, tmp:block$res -> block$res21, emptyEnv -> emptyEnv, apply -> apply, tmp:block$res -> block$res6, tmp:tmp -> tmp29, tmp:block$res -> block$res22, compose -> compose, member:Subst -> Subst1, class:Subst -> Subst, member:Gen -> Gen1, class:Gen -> Gen, tmp:tmp -> tmp30, tmp:tmp -> tmp31, tmp:tmp -> tmp32, tmp:tmp -> tmp33, tmp:tmp -> tmp34, tmp:tmp -> tmp35, tmp:tmp -> tmp36, tmp:tmp -> tmp37, tmp:tmp -> tmp38, tmp:tmp -> tmp39, tmp:tmp -> tmp40, class:Term -> Term1, tmp:tmp -> tmp41, tmp:tmp -> tmp42, tmp:tmp -> tmp43, tmp:block$res -> block$res26, class:Var -> Var, tmp:block$res -> block$res27, env -> env, term -> term, tmp:block$res -> block$res23, member:instance$Ident(Gen) -> instance$Ident$_Gen$_, tmp:tmp -> tmp44, class:IntLit -> IntLit, tmp:tmp -> tmp45, tmp:inlinedVal -> inlinedVal4, tmp:block$res -> block$res28, class:BoolLit -> BoolLit, env -> env1)
-//│     defaultImportBindings = HashMap(/storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Iter.mjs -> Iter, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Option.mjs -> Option, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Runtime.mjs -> Runtime, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Predef.mjs -> Predef)
-//│ ═══[COMPILATION ERROR] No definition found in scope for member 'infer$tailrec'
-//│ FAILURE: Unexpected runtime error
-//│ FAILURE LOCATION: mkQuery (JSBackendDiffMaker.scala:259)
-//│ ═══[RUNTIME ERROR] ReferenceError: infer$tailrec is not defined
-//│     at REPL112:1:283
-//│     at ContextifyScript.runInThisContext (node:vm:138:12)
-//│     at defaultEval (node:repl:608:24)
-//│     at REPLEvalInContext (node:repl:691:9)
-//│     at AsyncLocalStorage.run (node:internal/async_local_storage/async_context_frame:66:14)
-//│     at REPLServer.REPLEval [as eval] (node:repl:690:19)
-//│     at REPLServer.onLine (node:repl:828:12)
-//│     at REPLServer.emit (node:events:514:20)
-//│     at [_onLine] [as _onLine] (node:internal/readline/interface:474:12)
-//│     at [_normalWrite] [as _normalWrite] (node:internal/readline/interface:669:18)
-//│ FAILURE: Unexpected runtime error
-//│ FAILURE LOCATION: processIRBlock (JSBackendDiffMaker.scala:299)
-//│ ═══[RUNTIME ERROR] Expected: '"Int"', got: 'undefined'
+//│ = "Int"
 
 :expect "Int"
 emptyEnv |-  App(id, App(id, IntLit(5)))
-//│ FAILURE: Unexpected compilation error
-//│ FAILURE LOCATION: lookup_! (Scope.scala:136)
-//│ FAILURE INFO: Tuple2:
-//│   _1 = Tuple2:
-//│     _1 = member:infer$tailrec⁰
-//│     _2 = class hkmc2.semantics.BlockMemberSymbol
-//│   _2 = Scope:
-//│     parentOrCfg = Left of Cfg:
-//│       escapeChars = true
-//│       useSuperscripts = false
-//│       includeZero = false
-//│       defaultName = "tmp"
-//│     curThis = S of S of globalThis:globalThis⁰
-//│     bindings = HashMap(term -> term1, member:instance$Ident(Gen) -> instance$Ident$_Gen$_1, tmp:runtime -> runtime, tmp:block$res -> block$res12, tmp:tmp -> tmp46, tmp:definitionMetadata -> definitionMetadata, tmp:tmp -> tmp47, tmp:prettyPrint -> prettyPrint, tmp:inlinedVal -> inlinedVal5, tmp:Term -> Term, tmp:Block -> Block, tmp:tmp -> tmp1, tmp:block$res -> block$res29, tmp:option -> option, tmp:block$res -> block$res13, env -> env2, term -> term2, t1 -> t1, t2 -> t2, member:instance$Ident(Gen) -> instance$Ident$_Gen$_2, tmp:inlinedVal -> inlinedVal, tmp:tmp -> tmp48, tmp:tmp -> tmp49, tmp:tmp -> tmp2, tmp:inlinedVal -> inlinedVal6, tmp:scrut -> scrut, tmp:block$res -> block$res14, tmp:block$res -> block$res30, env -> env3, term -> term3, tmp:tmp -> tmp3, tmp:tmp -> tmp4, tmp:block$res -> block$res15, member:instance$Ident(Gen) -> instance$Ident$_Gen$_3, tmp:tmp -> tmp50, tmp:tmp -> tmp51, tmp:inlinedVal -> inlinedVal7, tmp:tmp -> tmp5, tmp:block$res -> block$res31, t2 -> t21, tmp:inlinedVal -> inlinedVal1, tmp:tmp -> tmp52, env -> env4, tmp:block$res -> block$res, tmp:tmp -> tmp6, tmp:scrut -> scrut1, tmp:block$res -> block$res1, tmp:block$res -> block$res16, member:instance$Ident(Gen) -> instance$Ident$_Gen$_4, tmp:block$res -> block$res2, tmp:tmp -> tmp53, tmp:tmp -> tmp54, tmp:inlinedVal -> inlinedVal8, member:Option -> Option, tmp:block$res -> block$res32, member:Type -> Type1, member:TVar -> TVar1, member:TFun -> TFun1, tmp:tmp -> tmp7, tmp:tmp -> tmp55, member:TPrim -> TPrim1, tmp:tmp -> tmp8, env -> env5, class:Type -> Type, tmp:tmp -> tmp9, tmp:tmp -> tmp10, tmp:tmp -> tmp11, tmp:tmp -> tmp12, member:instance$Ident(Gen) -> instance$Ident$_Gen$_5, class:TFun -> TFun, tmp:tmp -> tmp13, tmp:tmp -> tmp56, tmp:block$res -> block$res17, tmp:tmp -> tmp57, tmp:inlinedVal -> inlinedVal9, tmp:block$res -> block$res33, tmp:tmp -> tmp58, tmp:tmp -> tmp59, tmp:tmp -> tmp14, env -> env6, tmp:tmp -> tmp15, tmp:tmp -> tmp16, tmp:tmp -> tmp17, tmp:tmp -> tmp18, member:instance$Ident(Gen) -> instance$Ident$_Gen$_6, tmp:tmp -> tmp19, tmp:tmp -> tmp60, tmp:tmp -> tmp61, tmp:inlinedVal -> inlinedVal10, tmp:inlinedVal -> inlinedVal2, tmp:block$res -> block$res34, tmp:tmp -> tmp20, tmp:scrut -> scrut2, tmp:block$res -> block$res18, tmp:tmp -> tmp62, tmp:tmp -> tmp63, tmp:tmp -> tmp64, tmp:block$res -> block$res7, env -> env7, emptySub -> emptySub, tmp:tmp -> tmp21, tmp:tmp -> tmp22, tmp:tmp -> tmp23, member:instance$Ident(Gen) -> instance$Ident$_Gen$_7, tmp:tmp -> tmp, tmp:tmp -> tmp24, tmp:tmp -> tmp65, member:Predef -> Predef, tmp:block$res -> block$res8, tmp:block$res -> block$res19, tmp:tmp -> tmp66, tmp:inlinedVal -> inlinedVal11, member:applyPattern -> applyPattern, tmp:block$res -> block$res35, tmp:tmp -> tmp25, tmp:tmp -> tmp26, tmp:tmp -> tmp27, tmp:inlinedVal -> inlinedVal3, tmp:block$res -> block$res9, tmp:tmp -> tmp28, tmp:scrut -> scrut3, member:Unify -> Unify1, tmp:block$res -> block$res20, pattern:Unify -> Unify, member:Env -> Env1, class:Env -> Env, member:Iter -> Iter, class:TVar -> TVar, class:TPrim -> TPrim, member:Runtime -> Runtime, tmp:block$res -> block$res3, TInt -> TInt, TBool -> TBool, tmp:block$res -> block$res4, member:Term -> Term2, member:IntLit -> IntLit1, member:Var -> Var1, member:App -> App1, member:Abs -> Abs1, member:BoolLit -> BoolLit1, member:ShowTerm -> ShowTerm1, pattern:ShowTerm -> ShowTerm, class:Abs -> Abs, class:App -> App, tmp:block$res -> block$res21, emptyEnv -> emptyEnv, tmp:tmp -> tmp29, tmp:block$res -> block$res22, member:Gen -> Gen1, class:Gen -> Gen, class:Term -> Term1, class:Var -> Var, tmp:block$res -> block$res23, class:IntLit -> IntLit, class:BoolLit -> BoolLit, member:lambda$ -> lambda$, member:inferTop -> inferTop, tmp:block$res -> block$res5, member:Scheme -> Scheme1, class:Scheme -> Scheme, tmp:block$res -> block$res24, tmp:block$res -> block$res10, member:unify' -> unify$_, member:inferType -> inferType, tmp:block$res -> block$res11, member:unify -> unify, tmp:block$res -> block$res25, id -> id, const -> const1, apply -> apply, tmp:block$res -> block$res6, compose -> compose, member:Subst -> Subst1, class:Subst -> Subst, tmp:tmp -> tmp30, tmp:tmp -> tmp31, tmp:tmp -> tmp32, tmp:tmp -> tmp33, tmp:tmp -> tmp34, tmp:tmp -> tmp35, tmp:tmp -> tmp36, tmp:tmp -> tmp37, tmp:tmp -> tmp38, tmp:tmp -> tmp39, tmp:tmp -> tmp40, tmp:tmp -> tmp41, tmp:tmp -> tmp42, tmp:tmp -> tmp43, tmp:block$res -> block$res26, tmp:block$res -> block$res27, env -> env, term -> term, member:instance$Ident(Gen) -> instance$Ident$_Gen$_, tmp:tmp -> tmp44, tmp:tmp -> tmp45, tmp:inlinedVal -> inlinedVal4, tmp:block$res -> block$res28, env -> env1)
-//│     defaultImportBindings = HashMap(/storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Iter.mjs -> Iter, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Option.mjs -> Option, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Runtime.mjs -> Runtime, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Predef.mjs -> Predef)
-//│ ═══[COMPILATION ERROR] No definition found in scope for member 'infer$tailrec'
-//│ FAILURE: Unexpected runtime error
-//│ FAILURE LOCATION: mkQuery (JSBackendDiffMaker.scala:259)
-//│ ═══[RUNTIME ERROR] ReferenceError: infer$tailrec is not defined
-//│     at REPL115:1:334
-//│     at ContextifyScript.runInThisContext (node:vm:138:12)
-//│     at defaultEval (node:repl:608:24)
-//│     at REPLEvalInContext (node:repl:691:9)
-//│     at AsyncLocalStorage.run (node:internal/async_local_storage/async_context_frame:66:14)
-//│     at REPLServer.REPLEval [as eval] (node:repl:690:19)
-//│     at REPLServer.onLine (node:repl:828:12)
-//│     at REPLServer.emit (node:events:514:20)
-//│     at [_onLine] [as _onLine] (node:internal/readline/interface:474:12)
-//│     at [_normalWrite] [as _normalWrite] (node:internal/readline/interface:669:18)
-//│ FAILURE: Unexpected runtime error
-//│ FAILURE LOCATION: processIRBlock (JSBackendDiffMaker.scala:299)
-//│ ═══[RUNTIME ERROR] Expected: '"Int"', got: 'undefined'
+//│ = "Int"
 
 :silent
 let env1 = emptyEnv.extend of
@@ -601,73 +304,11 @@ let env1 = emptyEnv.extend of
 
 :expect "Int"
 env1 |- App(Var("id"), IntLit(5))
-//│ FAILURE: Unexpected compilation error
-//│ FAILURE LOCATION: lookup_! (Scope.scala:136)
-//│ FAILURE INFO: Tuple2:
-//│   _1 = Tuple2:
-//│     _1 = member:infer$tailrec⁰
-//│     _2 = class hkmc2.semantics.BlockMemberSymbol
-//│   _2 = Scope:
-//│     parentOrCfg = Left of Cfg:
-//│       escapeChars = true
-//│       useSuperscripts = false
-//│       includeZero = false
-//│       defaultName = "tmp"
-//│     curThis = S of S of globalThis:globalThis⁰
-//│     bindings = HashMap(term -> term1, member:instance$Ident(Gen) -> instance$Ident$_Gen$_1, tmp:runtime -> runtime, tmp:block$res -> block$res12, tmp:tmp -> tmp46, tmp:definitionMetadata -> definitionMetadata, tmp:tmp -> tmp47, tmp:prettyPrint -> prettyPrint, tmp:inlinedVal -> inlinedVal5, tmp:Term -> Term, tmp:Block -> Block, tmp:tmp -> tmp1, tmp:block$res -> block$res29, tmp:option -> option, tmp:block$res -> block$res13, env -> env2, term -> term2, t1 -> t1, t2 -> t2, member:instance$Ident(Gen) -> instance$Ident$_Gen$_2, tmp:inlinedVal -> inlinedVal, tmp:tmp -> tmp48, tmp:tmp -> tmp49, tmp:tmp -> tmp2, tmp:inlinedVal -> inlinedVal6, tmp:scrut -> scrut, tmp:block$res -> block$res14, tmp:block$res -> block$res30, env -> env3, term -> term3, tmp:tmp -> tmp3, tmp:tmp -> tmp4, tmp:block$res -> block$res15, member:instance$Ident(Gen) -> instance$Ident$_Gen$_3, tmp:tmp -> tmp50, tmp:tmp -> tmp51, tmp:inlinedVal -> inlinedVal7, tmp:tmp -> tmp5, tmp:block$res -> block$res31, t2 -> t21, tmp:inlinedVal -> inlinedVal1, tmp:tmp -> tmp52, env -> env4, tmp:block$res -> block$res, tmp:tmp -> tmp6, tmp:scrut -> scrut1, tmp:block$res -> block$res1, tmp:block$res -> block$res16, member:instance$Ident(Gen) -> instance$Ident$_Gen$_4, tmp:block$res -> block$res2, tmp:tmp -> tmp53, tmp:tmp -> tmp54, tmp:inlinedVal -> inlinedVal8, member:Option -> Option, tmp:block$res -> block$res32, member:Type -> Type1, member:TVar -> TVar1, member:TFun -> TFun1, tmp:tmp -> tmp7, tmp:tmp -> tmp55, member:TPrim -> TPrim1, tmp:tmp -> tmp8, env -> env5, class:Type -> Type, tmp:tmp -> tmp9, tmp:tmp -> tmp10, tmp:tmp -> tmp11, tmp:tmp -> tmp12, member:instance$Ident(Gen) -> instance$Ident$_Gen$_5, class:TFun -> TFun, tmp:tmp -> tmp13, tmp:tmp -> tmp56, tmp:block$res -> block$res17, tmp:tmp -> tmp57, tmp:inlinedVal -> inlinedVal9, tmp:block$res -> block$res33, tmp:tmp -> tmp58, tmp:tmp -> tmp59, tmp:tmp -> tmp14, env -> env6, tmp:tmp -> tmp15, tmp:tmp -> tmp16, tmp:tmp -> tmp17, tmp:tmp -> tmp18, member:instance$Ident(Gen) -> instance$Ident$_Gen$_6, tmp:tmp -> tmp19, tmp:tmp -> tmp60, tmp:tmp -> tmp61, tmp:inlinedVal -> inlinedVal10, tmp:inlinedVal -> inlinedVal2, tmp:block$res -> block$res34, tmp:tmp -> tmp20, tmp:scrut -> scrut2, tmp:block$res -> block$res18, tmp:tmp -> tmp62, tmp:tmp -> tmp63, tmp:tmp -> tmp64, tmp:block$res -> block$res7, env -> env7, emptySub -> emptySub, tmp:tmp -> tmp21, tmp:tmp -> tmp22, tmp:tmp -> tmp23, member:instance$Ident(Gen) -> instance$Ident$_Gen$_7, tmp:tmp -> tmp, tmp:tmp -> tmp24, tmp:tmp -> tmp65, member:Predef -> Predef, tmp:block$res -> block$res8, tmp:block$res -> block$res19, tmp:tmp -> tmp66, tmp:inlinedVal -> inlinedVal11, member:applyPattern -> applyPattern, tmp:block$res -> block$res35, env1 -> env11, tmp:tmp -> tmp25, tmp:tmp -> tmp26, tmp:tmp -> tmp27, tmp:inlinedVal -> inlinedVal3, tmp:tmp -> tmp67, tmp:tmp -> tmp68, tmp:block$res -> block$res9, tmp:tmp -> tmp28, tmp:tmp -> tmp69, tmp:scrut -> scrut3, tmp:tmp -> tmp70, member:Unify -> Unify1, tmp:block$res -> block$res20, tmp:tmp -> tmp71, pattern:Unify -> Unify, tmp:tmp -> tmp72, tmp:block$res -> block$res36, member:Env -> Env1, class:Env -> Env, tmp:tmp -> tmp73, tmp:tmp -> tmp74, member:Iter -> Iter, tmp:tmp -> tmp75, class:TVar -> TVar, env -> env8, member:instance$Ident(Gen) -> instance$Ident$_Gen$_8, tmp:tmp -> tmp76, tmp:tmp -> tmp77, tmp:inlinedVal -> inlinedVal12, tmp:block$res -> block$res37, class:TPrim -> TPrim, member:Runtime -> Runtime, tmp:block$res -> block$res3, TInt -> TInt, TBool -> TBool, tmp:block$res -> block$res4, member:Term -> Term2, member:IntLit -> IntLit1, member:Var -> Var1, member:App -> App1, member:Abs -> Abs1, member:BoolLit -> BoolLit1, member:ShowTerm -> ShowTerm1, pattern:ShowTerm -> ShowTerm, class:Abs -> Abs, class:App -> App, tmp:block$res -> block$res21, emptyEnv -> emptyEnv, tmp:tmp -> tmp29, tmp:block$res -> block$res22, member:Gen -> Gen1, class:Gen -> Gen, class:Term -> Term1, class:Var -> Var, tmp:block$res -> block$res23, class:IntLit -> IntLit, class:BoolLit -> BoolLit, member:lambda$ -> lambda$, member:inferTop -> inferTop, tmp:block$res -> block$res5, member:Scheme -> Scheme1, class:Scheme -> Scheme, tmp:block$res -> block$res24, tmp:block$res -> block$res10, member:unify' -> unify$_, member:inferType -> inferType, tmp:block$res -> block$res11, member:unify -> unify, tmp:block$res -> block$res25, id -> id, const -> const1, apply -> apply, tmp:block$res -> block$res6, compose -> compose, member:Subst -> Subst1, class:Subst -> Subst, tmp:tmp -> tmp30, tmp:tmp -> tmp31, tmp:tmp -> tmp32, tmp:tmp -> tmp33, tmp:tmp -> tmp34, tmp:tmp -> tmp35, tmp:tmp -> tmp36, tmp:tmp -> tmp37, tmp:tmp -> tmp38, tmp:tmp -> tmp39, tmp:tmp -> tmp40, tmp:tmp -> tmp41, tmp:tmp -> tmp42, tmp:tmp -> tmp43, tmp:block$res -> block$res26, tmp:block$res -> block$res27, env -> env, term -> term, member:instance$Ident(Gen) -> instance$Ident$_Gen$_, tmp:tmp -> tmp44, tmp:tmp -> tmp45, tmp:inlinedVal -> inlinedVal4, tmp:block$res -> block$res28, env -> env1)
-//│     defaultImportBindings = HashMap(/storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Iter.mjs -> Iter, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Option.mjs -> Option, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Runtime.mjs -> Runtime, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Predef.mjs -> Predef)
-//│ ═══[COMPILATION ERROR] No definition found in scope for member 'infer$tailrec'
-//│ FAILURE: Unexpected runtime error
-//│ FAILURE LOCATION: mkQuery (JSBackendDiffMaker.scala:259)
-//│ ═══[RUNTIME ERROR] ReferenceError: infer$tailrec is not defined
-//│     at REPL120:1:329
-//│     at ContextifyScript.runInThisContext (node:vm:138:12)
-//│     at defaultEval (node:repl:608:24)
-//│     at REPLEvalInContext (node:repl:691:9)
-//│     at AsyncLocalStorage.run (node:internal/async_local_storage/async_context_frame:66:14)
-//│     at REPLServer.REPLEval [as eval] (node:repl:690:19)
-//│     at REPLServer.onLine (node:repl:828:12)
-//│     at REPLServer.emit (node:events:514:20)
-//│     at [_onLine] [as _onLine] (node:internal/readline/interface:474:12)
-//│     at [_normalWrite] [as _normalWrite] (node:internal/readline/interface:669:18)
-//│ FAILURE: Unexpected runtime error
-//│ FAILURE LOCATION: processIRBlock (JSBackendDiffMaker.scala:299)
-//│ ═══[RUNTIME ERROR] Expected: '"Int"', got: 'undefined'
+//│ = "Int"
 
 :expect "Bool"
 env1 |- App(Var("id"), BoolLit(true))
-//│ FAILURE: Unexpected compilation error
-//│ FAILURE LOCATION: lookup_! (Scope.scala:136)
-//│ FAILURE INFO: Tuple2:
-//│   _1 = Tuple2:
-//│     _1 = member:infer$tailrec⁰
-//│     _2 = class hkmc2.semantics.BlockMemberSymbol
-//│   _2 = Scope:
-//│     parentOrCfg = Left of Cfg:
-//│       escapeChars = true
-//│       useSuperscripts = false
-//│       includeZero = false
-//│       defaultName = "tmp"
-//│     curThis = S of S of globalThis:globalThis⁰
-//│     bindings = HashMap(term -> term1, member:instance$Ident(Gen) -> instance$Ident$_Gen$_1, tmp:runtime -> runtime, tmp:block$res -> block$res12, tmp:tmp -> tmp46, tmp:definitionMetadata -> definitionMetadata, tmp:tmp -> tmp47, tmp:prettyPrint -> prettyPrint, tmp:inlinedVal -> inlinedVal5, tmp:Term -> Term, tmp:Block -> Block, tmp:tmp -> tmp1, tmp:block$res -> block$res29, tmp:option -> option, tmp:block$res -> block$res13, env -> env2, term -> term2, t1 -> t1, t2 -> t2, member:instance$Ident(Gen) -> instance$Ident$_Gen$_2, tmp:inlinedVal -> inlinedVal, tmp:tmp -> tmp48, tmp:tmp -> tmp49, tmp:tmp -> tmp2, tmp:inlinedVal -> inlinedVal6, tmp:scrut -> scrut, tmp:block$res -> block$res14, tmp:block$res -> block$res30, env -> env3, term -> term3, tmp:tmp -> tmp3, tmp:tmp -> tmp4, tmp:block$res -> block$res15, member:instance$Ident(Gen) -> instance$Ident$_Gen$_3, tmp:tmp -> tmp50, tmp:tmp -> tmp51, tmp:inlinedVal -> inlinedVal7, tmp:tmp -> tmp5, tmp:block$res -> block$res31, t2 -> t21, tmp:inlinedVal -> inlinedVal1, tmp:tmp -> tmp52, env -> env4, tmp:block$res -> block$res, tmp:tmp -> tmp6, tmp:scrut -> scrut1, tmp:block$res -> block$res1, tmp:block$res -> block$res16, member:instance$Ident(Gen) -> instance$Ident$_Gen$_4, tmp:block$res -> block$res2, tmp:tmp -> tmp53, tmp:tmp -> tmp54, tmp:inlinedVal -> inlinedVal8, member:Option -> Option, tmp:block$res -> block$res32, member:Type -> Type1, member:TVar -> TVar1, member:TFun -> TFun1, tmp:tmp -> tmp7, tmp:tmp -> tmp55, member:TPrim -> TPrim1, tmp:tmp -> tmp8, env -> env5, class:Type -> Type, tmp:tmp -> tmp9, tmp:tmp -> tmp10, tmp:tmp -> tmp11, tmp:tmp -> tmp12, member:instance$Ident(Gen) -> instance$Ident$_Gen$_5, class:TFun -> TFun, tmp:tmp -> tmp13, tmp:tmp -> tmp56, tmp:block$res -> block$res17, tmp:tmp -> tmp57, tmp:inlinedVal -> inlinedVal9, tmp:block$res -> block$res33, tmp:tmp -> tmp58, tmp:tmp -> tmp59, tmp:tmp -> tmp14, env -> env6, tmp:tmp -> tmp15, tmp:tmp -> tmp16, tmp:tmp -> tmp17, tmp:tmp -> tmp18, member:instance$Ident(Gen) -> instance$Ident$_Gen$_6, tmp:tmp -> tmp19, tmp:tmp -> tmp60, tmp:tmp -> tmp61, tmp:inlinedVal -> inlinedVal10, tmp:inlinedVal -> inlinedVal2, tmp:block$res -> block$res34, tmp:tmp -> tmp20, tmp:scrut -> scrut2, tmp:block$res -> block$res18, tmp:tmp -> tmp62, tmp:tmp -> tmp63, tmp:tmp -> tmp64, tmp:block$res -> block$res7, env -> env7, emptySub -> emptySub, tmp:tmp -> tmp21, tmp:tmp -> tmp22, tmp:tmp -> tmp23, member:instance$Ident(Gen) -> instance$Ident$_Gen$_7, tmp:tmp -> tmp, tmp:tmp -> tmp24, tmp:tmp -> tmp65, member:Predef -> Predef, tmp:block$res -> block$res8, tmp:block$res -> block$res19, tmp:tmp -> tmp66, tmp:inlinedVal -> inlinedVal11, member:applyPattern -> applyPattern, tmp:block$res -> block$res35, env1 -> env11, tmp:tmp -> tmp25, tmp:tmp -> tmp26, tmp:tmp -> tmp27, tmp:inlinedVal -> inlinedVal3, tmp:tmp -> tmp67, tmp:tmp -> tmp68, tmp:block$res -> block$res9, tmp:tmp -> tmp28, tmp:tmp -> tmp69, tmp:scrut -> scrut3, tmp:tmp -> tmp70, member:Unify -> Unify1, tmp:block$res -> block$res20, tmp:tmp -> tmp71, pattern:Unify -> Unify, tmp:tmp -> tmp72, tmp:block$res -> block$res36, member:Env -> Env1, class:Env -> Env, tmp:tmp -> tmp73, tmp:tmp -> tmp74, member:Iter -> Iter, tmp:tmp -> tmp75, class:TVar -> TVar, env -> env8, member:instance$Ident(Gen) -> instance$Ident$_Gen$_8, tmp:tmp -> tmp76, tmp:tmp -> tmp77, tmp:inlinedVal -> inlinedVal12, tmp:block$res -> block$res37, class:TPrim -> TPrim, tmp:tmp -> tmp78, member:Runtime -> Runtime, tmp:tmp -> tmp79, tmp:tmp -> tmp80, env -> env9, member:instance$Ident(Gen) -> instance$Ident$_Gen$_9, tmp:tmp -> tmp81, tmp:tmp -> tmp82, tmp:inlinedVal -> inlinedVal13, tmp:block$res -> block$res38, tmp:block$res -> block$res3, TInt -> TInt, TBool -> TBool, tmp:block$res -> block$res4, member:Term -> Term2, member:IntLit -> IntLit1, member:Var -> Var1, member:App -> App1, member:Abs -> Abs1, member:BoolLit -> BoolLit1, member:ShowTerm -> ShowTerm1, pattern:ShowTerm -> ShowTerm, class:Abs -> Abs, class:App -> App, tmp:block$res -> block$res21, emptyEnv -> emptyEnv, tmp:tmp -> tmp29, tmp:block$res -> block$res22, member:Gen -> Gen1, class:Gen -> Gen, class:Term -> Term1, class:Var -> Var, tmp:block$res -> block$res23, class:IntLit -> IntLit, class:BoolLit -> BoolLit, member:lambda$ -> lambda$, member:inferTop -> inferTop, tmp:block$res -> block$res5, member:Scheme -> Scheme1, class:Scheme -> Scheme, tmp:block$res -> block$res24, tmp:block$res -> block$res10, member:unify' -> unify$_, member:inferType -> inferType, tmp:block$res -> block$res11, member:unify -> unify, tmp:block$res -> block$res25, id -> id, const -> const1, apply -> apply, tmp:block$res -> block$res6, compose -> compose, member:Subst -> Subst1, class:Subst -> Subst, tmp:tmp -> tmp30, tmp:tmp -> tmp31, tmp:tmp -> tmp32, tmp:tmp -> tmp33, tmp:tmp -> tmp34, tmp:tmp -> tmp35, tmp:tmp -> tmp36, tmp:tmp -> tmp37, tmp:tmp -> tmp38, tmp:tmp -> tmp39, tmp:tmp -> tmp40, tmp:tmp -> tmp41, tmp:tmp -> tmp42, tmp:tmp -> tmp43, tmp:block$res -> block$res26, tmp:block$res -> block$res27, env -> env, term -> term, member:instance$Ident(Gen) -> instance$Ident$_Gen$_, tmp:tmp -> tmp44, tmp:tmp -> tmp45, tmp:inlinedVal -> inlinedVal4, tmp:block$res -> block$res28, env -> env1)
-//│     defaultImportBindings = HashMap(/storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Iter.mjs -> Iter, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Option.mjs -> Option, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Runtime.mjs -> Runtime, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Predef.mjs -> Predef)
-//│ ═══[COMPILATION ERROR] No definition found in scope for member 'infer$tailrec'
-//│ FAILURE: Unexpected runtime error
-//│ FAILURE LOCATION: mkQuery (JSBackendDiffMaker.scala:259)
-//│ ═══[RUNTIME ERROR] ReferenceError: infer$tailrec is not defined
-//│     at REPL123:1:333
-//│     at ContextifyScript.runInThisContext (node:vm:138:12)
-//│     at defaultEval (node:repl:608:24)
-//│     at REPLEvalInContext (node:repl:691:9)
-//│     at AsyncLocalStorage.run (node:internal/async_local_storage/async_context_frame:66:14)
-//│     at REPLServer.REPLEval [as eval] (node:repl:690:19)
-//│     at REPLServer.onLine (node:repl:828:12)
-//│     at REPLServer.emit (node:events:514:20)
-//│     at [_onLine] [as _onLine] (node:internal/readline/interface:474:12)
-//│     at [_normalWrite] [as _normalWrite] (node:internal/readline/interface:669:18)
-//│ FAILURE: Unexpected runtime error
-//│ FAILURE LOCATION: processIRBlock (JSBackendDiffMaker.scala:299)
-//│ ═══[RUNTIME ERROR] Expected: '"Bool"', got: 'undefined'
+//│ = "Bool"
 
 :silent
 let env2 = env1.extend of
@@ -675,55 +316,11 @@ let env2 = env1.extend of
   Scheme(new Set(), TFun(TInt, TFun(TInt, TInt)))
 
 env2 |- App(App(Var("add"), IntLit(5)), IntLit(5))
-//│ FAILURE: Unexpected compilation error
-//│ FAILURE LOCATION: lookup_! (Scope.scala:136)
-//│ FAILURE INFO: Tuple2:
-//│   _1 = Tuple2:
-//│     _1 = member:infer$tailrec⁰
-//│     _2 = class hkmc2.semantics.BlockMemberSymbol
-//│   _2 = Scope:
-//│     parentOrCfg = Left of Cfg:
-//│       escapeChars = true
-//│       useSuperscripts = false
-//│       includeZero = false
-//│       defaultName = "tmp"
-//│     curThis = S of S of globalThis:globalThis⁰
-//│     bindings = HashMap(term -> term1, member:instance$Ident(Gen) -> instance$Ident$_Gen$_1, tmp:runtime -> runtime, tmp:block$res -> block$res12, tmp:tmp -> tmp46, tmp:definitionMetadata -> definitionMetadata, tmp:tmp -> tmp47, tmp:prettyPrint -> prettyPrint, tmp:inlinedVal -> inlinedVal5, tmp:Term -> Term, tmp:Block -> Block, tmp:tmp -> tmp1, tmp:block$res -> block$res29, tmp:option -> option, tmp:block$res -> block$res13, env -> env2, term -> term2, t1 -> t1, t2 -> t2, member:instance$Ident(Gen) -> instance$Ident$_Gen$_2, tmp:inlinedVal -> inlinedVal, tmp:tmp -> tmp48, tmp:tmp -> tmp49, tmp:tmp -> tmp2, tmp:inlinedVal -> inlinedVal6, tmp:scrut -> scrut, tmp:block$res -> block$res14, tmp:block$res -> block$res30, env -> env3, term -> term3, tmp:tmp -> tmp3, tmp:tmp -> tmp4, tmp:block$res -> block$res15, member:instance$Ident(Gen) -> instance$Ident$_Gen$_3, tmp:tmp -> tmp50, tmp:tmp -> tmp51, tmp:inlinedVal -> inlinedVal7, tmp:tmp -> tmp5, tmp:block$res -> block$res31, t2 -> t21, tmp:inlinedVal -> inlinedVal1, tmp:tmp -> tmp52, env -> env4, tmp:block$res -> block$res, tmp:tmp -> tmp6, tmp:scrut -> scrut1, tmp:block$res -> block$res1, tmp:block$res -> block$res16, member:instance$Ident(Gen) -> instance$Ident$_Gen$_4, tmp:block$res -> block$res2, tmp:tmp -> tmp53, tmp:tmp -> tmp54, tmp:inlinedVal -> inlinedVal8, member:Option -> Option, tmp:block$res -> block$res32, member:Type -> Type1, member:TVar -> TVar1, member:TFun -> TFun1, tmp:tmp -> tmp7, tmp:tmp -> tmp55, member:TPrim -> TPrim1, tmp:tmp -> tmp8, env -> env5, class:Type -> Type, tmp:tmp -> tmp9, tmp:tmp -> tmp10, tmp:tmp -> tmp11, tmp:tmp -> tmp12, member:instance$Ident(Gen) -> instance$Ident$_Gen$_5, class:TFun -> TFun, tmp:tmp -> tmp13, tmp:tmp -> tmp56, tmp:block$res -> block$res17, tmp:tmp -> tmp57, tmp:inlinedVal -> inlinedVal9, tmp:block$res -> block$res33, tmp:tmp -> tmp58, tmp:tmp -> tmp59, tmp:tmp -> tmp14, env -> env6, tmp:tmp -> tmp15, tmp:tmp -> tmp16, tmp:tmp -> tmp17, tmp:tmp -> tmp18, member:instance$Ident(Gen) -> instance$Ident$_Gen$_6, tmp:tmp -> tmp19, tmp:tmp -> tmp60, tmp:tmp -> tmp61, tmp:inlinedVal -> inlinedVal10, tmp:inlinedVal -> inlinedVal2, tmp:block$res -> block$res34, tmp:tmp -> tmp20, tmp:scrut -> scrut2, tmp:block$res -> block$res18, tmp:tmp -> tmp62, tmp:tmp -> tmp63, tmp:tmp -> tmp64, tmp:block$res -> block$res7, env -> env7, emptySub -> emptySub, tmp:tmp -> tmp21, tmp:tmp -> tmp22, tmp:tmp -> tmp23, member:instance$Ident(Gen) -> instance$Ident$_Gen$_7, tmp:tmp -> tmp, tmp:tmp -> tmp24, tmp:tmp -> tmp65, member:Predef -> Predef, tmp:block$res -> block$res8, tmp:block$res -> block$res19, tmp:tmp -> tmp66, tmp:inlinedVal -> inlinedVal11, member:applyPattern -> applyPattern, tmp:block$res -> block$res35, env1 -> env11, tmp:tmp -> tmp25, tmp:tmp -> tmp26, tmp:tmp -> tmp27, tmp:inlinedVal -> inlinedVal3, tmp:tmp -> tmp67, tmp:tmp -> tmp68, tmp:block$res -> block$res9, tmp:tmp -> tmp28, tmp:tmp -> tmp69, tmp:scrut -> scrut3, tmp:tmp -> tmp70, member:Unify -> Unify1, tmp:block$res -> block$res20, tmp:tmp -> tmp71, pattern:Unify -> Unify, tmp:tmp -> tmp72, tmp:block$res -> block$res36, member:Env -> Env1, class:Env -> Env, tmp:tmp -> tmp73, tmp:tmp -> tmp74, member:Iter -> Iter, tmp:tmp -> tmp75, class:TVar -> TVar, env -> env8, member:instance$Ident(Gen) -> instance$Ident$_Gen$_8, tmp:tmp -> tmp76, tmp:tmp -> tmp77, tmp:inlinedVal -> inlinedVal12, tmp:block$res -> block$res37, class:TPrim -> TPrim, tmp:tmp -> tmp78, member:Runtime -> Runtime, tmp:tmp -> tmp79, tmp:tmp -> tmp80, env -> env9, member:instance$Ident(Gen) -> instance$Ident$_Gen$_9, tmp:tmp -> tmp81, tmp:tmp -> tmp82, tmp:inlinedVal -> inlinedVal13, tmp:block$res -> block$res38, env2 -> env21, tmp:tmp -> tmp83, tmp:tmp -> tmp84, tmp:tmp -> tmp85, tmp:tmp -> tmp86, tmp:block$res -> block$res39, tmp:block$res -> block$res3, tmp:tmp -> tmp87, TInt -> TInt, tmp:tmp -> tmp88, tmp:tmp -> tmp89, TBool -> TBool, tmp:tmp -> tmp90, tmp:tmp -> tmp91, tmp:block$res -> block$res4, env -> env10, member:Term -> Term2, member:IntLit -> IntLit1, member:instance$Ident(Gen) -> instance$Ident$_Gen$_10, member:Var -> Var1, tmp:tmp -> tmp92, member:App -> App1, tmp:tmp -> tmp93, member:Abs -> Abs1, tmp:inlinedVal -> inlinedVal14, member:BoolLit -> BoolLit1, member:ShowTerm -> ShowTerm1, tmp:block$res -> block$res40, pattern:ShowTerm -> ShowTerm, class:Abs -> Abs, class:App -> App, tmp:block$res -> block$res21, emptyEnv -> emptyEnv, tmp:tmp -> tmp29, tmp:block$res -> block$res22, member:Gen -> Gen1, class:Gen -> Gen, class:Term -> Term1, class:Var -> Var, tmp:block$res -> block$res23, class:IntLit -> IntLit, class:BoolLit -> BoolLit, member:lambda$ -> lambda$, member:inferTop -> inferTop, tmp:block$res -> block$res5, member:Scheme -> Scheme1, class:Scheme -> Scheme, tmp:block$res -> block$res24, tmp:block$res -> block$res10, member:unify' -> unify$_, member:inferType -> inferType, tmp:block$res -> block$res11, member:unify -> unify, tmp:block$res -> block$res25, id -> id, const -> const1, apply -> apply, tmp:block$res -> block$res6, compose -> compose, member:Subst -> Subst1, class:Subst -> Subst, tmp:tmp -> tmp30, tmp:tmp -> tmp31, tmp:tmp -> tmp32, tmp:tmp -> tmp33, tmp:tmp -> tmp34, tmp:tmp -> tmp35, tmp:tmp -> tmp36, tmp:tmp -> tmp37, tmp:tmp -> tmp38, tmp:tmp -> tmp39, tmp:tmp -> tmp40, tmp:tmp -> tmp41, tmp:tmp -> tmp42, tmp:tmp -> tmp43, tmp:block$res -> block$res26, tmp:block$res -> block$res27, env -> env, term -> term, member:instance$Ident(Gen) -> instance$Ident$_Gen$_, tmp:tmp -> tmp44, tmp:tmp -> tmp45, tmp:inlinedVal -> inlinedVal4, tmp:block$res -> block$res28, env -> env1)
-//│     defaultImportBindings = HashMap(/storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Iter.mjs -> Iter, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Option.mjs -> Option, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Runtime.mjs -> Runtime, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Predef.mjs -> Predef)
-//│ ═══[COMPILATION ERROR] No definition found in scope for member 'infer$tailrec'
-//│ FAILURE: Unexpected runtime error
-//│ FAILURE LOCATION: mkQuery (JSBackendDiffMaker.scala:259)
-//│ ═══[RUNTIME ERROR] ReferenceError: infer$tailrec is not defined
-//│     at REPL128:1:434
-//│     at ContextifyScript.runInThisContext (node:vm:138:12)
-//│     at defaultEval (node:repl:608:24)
-//│     at REPLEvalInContext (node:repl:691:9)
-//│     at AsyncLocalStorage.run (node:internal/async_local_storage/async_context_frame:66:14)
-//│     at REPLServer.REPLEval [as eval] (node:repl:690:19)
-//│     at REPLServer.onLine (node:repl:828:12)
-//│     at REPLServer.emit (node:events:514:20)
-//│     at [_onLine] [as _onLine] (node:internal/readline/interface:474:12)
-//│     at [_normalWrite] [as _normalWrite] (node:internal/readline/interface:669:18)
+//│ = "Int"
 
 :re
 env2 |- App(App(Var("add"), IntLit(5)), BoolLit(true))
-//│ FAILURE: Unexpected compilation error
-//│ FAILURE LOCATION: lookup_! (Scope.scala:136)
-//│ FAILURE INFO: Tuple2:
-//│   _1 = Tuple2:
-//│     _1 = member:infer$tailrec⁰
-//│     _2 = class hkmc2.semantics.BlockMemberSymbol
-//│   _2 = Scope:
-//│     parentOrCfg = Left of Cfg:
-//│       escapeChars = true
-//│       useSuperscripts = false
-//│       includeZero = false
-//│       defaultName = "tmp"
-//│     curThis = S of S of globalThis:globalThis⁰
-//│     bindings = HashMap(term -> term1, member:instance$Ident(Gen) -> instance$Ident$_Gen$_1, tmp:runtime -> runtime, tmp:block$res -> block$res12, tmp:tmp -> tmp46, tmp:definitionMetadata -> definitionMetadata, tmp:tmp -> tmp47, tmp:prettyPrint -> prettyPrint, tmp:inlinedVal -> inlinedVal5, tmp:Term -> Term, tmp:Block -> Block, tmp:tmp -> tmp1, tmp:block$res -> block$res29, tmp:option -> option, tmp:block$res -> block$res13, env -> env2, term -> term2, t1 -> t1, t2 -> t2, member:instance$Ident(Gen) -> instance$Ident$_Gen$_2, tmp:inlinedVal -> inlinedVal, tmp:tmp -> tmp48, tmp:tmp -> tmp49, tmp:tmp -> tmp2, tmp:inlinedVal -> inlinedVal6, tmp:scrut -> scrut, tmp:block$res -> block$res14, tmp:block$res -> block$res30, env -> env3, term -> term3, tmp:tmp -> tmp3, tmp:tmp -> tmp4, tmp:block$res -> block$res15, member:instance$Ident(Gen) -> instance$Ident$_Gen$_3, tmp:tmp -> tmp50, tmp:tmp -> tmp51, tmp:inlinedVal -> inlinedVal7, tmp:tmp -> tmp5, tmp:block$res -> block$res31, t2 -> t21, tmp:inlinedVal -> inlinedVal1, tmp:tmp -> tmp52, env -> env4, tmp:block$res -> block$res, tmp:tmp -> tmp6, tmp:scrut -> scrut1, tmp:block$res -> block$res1, tmp:block$res -> block$res16, member:instance$Ident(Gen) -> instance$Ident$_Gen$_4, tmp:block$res -> block$res2, tmp:tmp -> tmp53, tmp:tmp -> tmp54, tmp:inlinedVal -> inlinedVal8, member:Option -> Option, tmp:block$res -> block$res32, member:Type -> Type1, member:TVar -> TVar1, member:TFun -> TFun1, tmp:tmp -> tmp7, tmp:tmp -> tmp55, member:TPrim -> TPrim1, tmp:tmp -> tmp8, env -> env5, class:Type -> Type, tmp:tmp -> tmp9, tmp:tmp -> tmp10, tmp:tmp -> tmp11, tmp:tmp -> tmp12, member:instance$Ident(Gen) -> instance$Ident$_Gen$_5, class:TFun -> TFun, tmp:tmp -> tmp13, tmp:tmp -> tmp56, tmp:block$res -> block$res17, tmp:tmp -> tmp57, tmp:inlinedVal -> inlinedVal9, tmp:block$res -> block$res33, tmp:tmp -> tmp58, tmp:tmp -> tmp59, tmp:tmp -> tmp14, env -> env6, tmp:tmp -> tmp15, tmp:tmp -> tmp16, tmp:tmp -> tmp17, tmp:tmp -> tmp18, member:instance$Ident(Gen) -> instance$Ident$_Gen$_6, tmp:tmp -> tmp19, tmp:tmp -> tmp60, tmp:tmp -> tmp61, tmp:inlinedVal -> inlinedVal10, tmp:inlinedVal -> inlinedVal2, tmp:block$res -> block$res34, tmp:tmp -> tmp20, tmp:scrut -> scrut2, tmp:block$res -> block$res18, tmp:tmp -> tmp62, tmp:tmp -> tmp63, tmp:tmp -> tmp64, tmp:block$res -> block$res7, env -> env7, emptySub -> emptySub, tmp:tmp -> tmp21, tmp:tmp -> tmp22, tmp:tmp -> tmp23, member:instance$Ident(Gen) -> instance$Ident$_Gen$_7, tmp:tmp -> tmp, tmp:tmp -> tmp24, tmp:tmp -> tmp65, member:Predef -> Predef, tmp:block$res -> block$res8, tmp:block$res -> block$res19, tmp:tmp -> tmp66, tmp:inlinedVal -> inlinedVal11, member:applyPattern -> applyPattern, tmp:block$res -> block$res35, env1 -> env11, tmp:tmp -> tmp25, tmp:tmp -> tmp26, tmp:tmp -> tmp27, tmp:inlinedVal -> inlinedVal3, tmp:tmp -> tmp67, tmp:tmp -> tmp68, tmp:block$res -> block$res9, tmp:tmp -> tmp28, tmp:tmp -> tmp69, tmp:scrut -> scrut3, tmp:tmp -> tmp70, member:Unify -> Unify1, tmp:block$res -> block$res20, tmp:tmp -> tmp71, pattern:Unify -> Unify, tmp:tmp -> tmp72, tmp:block$res -> block$res36, member:Env -> Env1, class:Env -> Env, tmp:tmp -> tmp73, tmp:tmp -> tmp74, member:Iter -> Iter, tmp:tmp -> tmp75, class:TVar -> TVar, env -> env8, member:instance$Ident(Gen) -> instance$Ident$_Gen$_8, tmp:tmp -> tmp76, tmp:tmp -> tmp77, tmp:inlinedVal -> inlinedVal12, tmp:block$res -> block$res37, class:TPrim -> TPrim, tmp:tmp -> tmp78, member:Runtime -> Runtime, tmp:tmp -> tmp79, tmp:tmp -> tmp80, env -> env9, member:instance$Ident(Gen) -> instance$Ident$_Gen$_9, tmp:tmp -> tmp81, tmp:tmp -> tmp82, tmp:inlinedVal -> inlinedVal13, tmp:block$res -> block$res38, env2 -> env21, tmp:tmp -> tmp83, tmp:tmp -> tmp84, tmp:tmp -> tmp85, tmp:tmp -> tmp86, tmp:block$res -> block$res39, tmp:block$res -> block$res3, tmp:tmp -> tmp87, TInt -> TInt, tmp:tmp -> tmp88, tmp:tmp -> tmp89, TBool -> TBool, tmp:tmp -> tmp90, tmp:tmp -> tmp91, tmp:block$res -> block$res4, env -> env10, member:Term -> Term2, member:IntLit -> IntLit1, member:instance$Ident(Gen) -> instance$Ident$_Gen$_10, member:Var -> Var1, tmp:tmp -> tmp92, member:App -> App1, tmp:tmp -> tmp93, member:Abs -> Abs1, tmp:inlinedVal -> inlinedVal14, member:BoolLit -> BoolLit1, member:ShowTerm -> ShowTerm1, tmp:block$res -> block$res40, pattern:ShowTerm -> ShowTerm, class:Abs -> Abs, tmp:tmp -> tmp94, tmp:tmp -> tmp95, tmp:tmp -> tmp96, tmp:tmp -> tmp97, tmp:tmp -> tmp98, env -> env12, class:App -> App, tmp:block$res -> block$res21, emptyEnv -> emptyEnv, member:instance$Ident(Gen) -> instance$Ident$_Gen$_11, tmp:tmp -> tmp99, tmp:tmp -> tmp29, tmp:tmp -> tmp100, tmp:block$res -> block$res22, tmp:inlinedVal -> inlinedVal15, tmp:block$res -> block$res41, member:Gen -> Gen1, class:Gen -> Gen, class:Term -> Term1, class:Var -> Var, tmp:block$res -> block$res23, class:IntLit -> IntLit, class:BoolLit -> BoolLit, member:lambda$ -> lambda$, member:inferTop -> inferTop, tmp:block$res -> block$res5, member:Scheme -> Scheme1, class:Scheme -> Scheme, tmp:block$res -> block$res24, tmp:block$res -> block$res10, member:unify' -> unify$_, member:inferType -> inferType, tmp:block$res -> block$res11, member:unify -> unify, tmp:block$res -> block$res25, id -> id, const -> const1, apply -> apply, tmp:block$res -> block$res6, compose -> compose, member:Subst -> Subst1, class:Subst -> Subst, tmp:tmp -> tmp30, tmp:tmp -> tmp31, tmp:tmp -> tmp32, tmp:tmp -> tmp33, tmp:tmp -> tmp34, tmp:tmp -> tmp35, tmp:tmp -> tmp36, tmp:tmp -> tmp37, tmp:tmp -> tmp38, tmp:tmp -> tmp39, tmp:tmp -> tmp40, tmp:tmp -> tmp41, tmp:tmp -> tmp42, tmp:tmp -> tmp43, tmp:block$res -> block$res26, tmp:block$res -> block$res27, env -> env, term -> term, member:instance$Ident(Gen) -> instance$Ident$_Gen$_, tmp:tmp -> tmp44, tmp:tmp -> tmp45, tmp:inlinedVal -> inlinedVal4, tmp:block$res -> block$res28, env -> env1)
-//│     defaultImportBindings = HashMap(/storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Iter.mjs -> Iter, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Option.mjs -> Option, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Runtime.mjs -> Runtime, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Predef.mjs -> Predef)
-//│ ═══[COMPILATION ERROR] No definition found in scope for member 'infer$tailrec'
-//│ ═══[RUNTIME ERROR] ReferenceError: infer$tailrec is not defined
+//│ ═══[RUNTIME ERROR] Error: Cannot unify Int with Bool
 
 :silent
 let env3 = env2.extend of
@@ -731,91 +328,19 @@ let env3 = env2.extend of
   Scheme(new Set(["a"]), TFun(TBool, TFun(TVar("a"), TFun(TVar("a"), TVar("a")))))
 
 env3 |- Var("if")
-//│ FAILURE: Unexpected compilation error
-//│ FAILURE LOCATION: lookup_! (Scope.scala:136)
-//│ FAILURE INFO: Tuple2:
-//│   _1 = Tuple2:
-//│     _1 = member:infer$tailrec⁰
-//│     _2 = class hkmc2.semantics.BlockMemberSymbol
-//│   _2 = Scope:
-//│     parentOrCfg = Left of Cfg:
-//│       escapeChars = true
-//│       useSuperscripts = false
-//│       includeZero = false
-//│       defaultName = "tmp"
-//│     curThis = S of S of globalThis:globalThis⁰
-//│     bindings = HashMap(term -> term1, member:instance$Ident(Gen) -> instance$Ident$_Gen$_1, tmp:runtime -> runtime, tmp:block$res -> block$res12, tmp:tmp -> tmp46, tmp:definitionMetadata -> definitionMetadata, tmp:tmp -> tmp47, tmp:prettyPrint -> prettyPrint, tmp:inlinedVal -> inlinedVal5, tmp:Term -> Term, tmp:Block -> Block, tmp:tmp -> tmp1, tmp:block$res -> block$res29, tmp:option -> option, tmp:block$res -> block$res13, env -> env2, term -> term2, t1 -> t1, t2 -> t2, member:instance$Ident(Gen) -> instance$Ident$_Gen$_2, tmp:inlinedVal -> inlinedVal, tmp:tmp -> tmp48, tmp:tmp -> tmp49, tmp:tmp -> tmp2, tmp:inlinedVal -> inlinedVal6, tmp:scrut -> scrut, tmp:block$res -> block$res14, tmp:block$res -> block$res30, env -> env3, term -> term3, tmp:tmp -> tmp3, tmp:tmp -> tmp4, tmp:block$res -> block$res15, member:instance$Ident(Gen) -> instance$Ident$_Gen$_3, tmp:tmp -> tmp50, tmp:tmp -> tmp51, tmp:inlinedVal -> inlinedVal7, tmp:tmp -> tmp5, tmp:block$res -> block$res31, t2 -> t21, tmp:inlinedVal -> inlinedVal1, tmp:tmp -> tmp52, env -> env4, tmp:block$res -> block$res, tmp:tmp -> tmp6, tmp:scrut -> scrut1, tmp:block$res -> block$res1, tmp:block$res -> block$res16, member:instance$Ident(Gen) -> instance$Ident$_Gen$_4, tmp:block$res -> block$res2, tmp:tmp -> tmp53, tmp:tmp -> tmp54, tmp:inlinedVal -> inlinedVal8, member:Option -> Option, tmp:block$res -> block$res32, member:Type -> Type1, member:TVar -> TVar1, member:TFun -> TFun1, tmp:tmp -> tmp7, tmp:tmp -> tmp55, member:TPrim -> TPrim1, tmp:tmp -> tmp8, env -> env5, class:Type -> Type, tmp:tmp -> tmp9, tmp:tmp -> tmp10, tmp:tmp -> tmp11, tmp:tmp -> tmp12, member:instance$Ident(Gen) -> instance$Ident$_Gen$_5, class:TFun -> TFun, tmp:tmp -> tmp13, tmp:tmp -> tmp56, tmp:block$res -> block$res17, tmp:tmp -> tmp57, tmp:inlinedVal -> inlinedVal9, tmp:block$res -> block$res33, tmp:tmp -> tmp58, tmp:tmp -> tmp59, tmp:tmp -> tmp14, env -> env6, tmp:tmp -> tmp15, tmp:tmp -> tmp16, tmp:tmp -> tmp17, tmp:tmp -> tmp18, member:instance$Ident(Gen) -> instance$Ident$_Gen$_6, tmp:tmp -> tmp19, tmp:tmp -> tmp60, tmp:tmp -> tmp61, tmp:inlinedVal -> inlinedVal10, tmp:inlinedVal -> inlinedVal2, tmp:block$res -> block$res34, tmp:tmp -> tmp20, tmp:scrut -> scrut2, tmp:block$res -> block$res18, tmp:tmp -> tmp62, tmp:tmp -> tmp63, tmp:tmp -> tmp64, tmp:block$res -> block$res7, env -> env7, emptySub -> emptySub, tmp:tmp -> tmp21, tmp:tmp -> tmp22, tmp:tmp -> tmp23, member:instance$Ident(Gen) -> instance$Ident$_Gen$_7, tmp:tmp -> tmp, tmp:tmp -> tmp24, tmp:tmp -> tmp65, member:Predef -> Predef, tmp:block$res -> block$res8, tmp:block$res -> block$res19, tmp:tmp -> tmp66, tmp:inlinedVal -> inlinedVal11, member:applyPattern -> applyPattern, tmp:block$res -> block$res35, env1 -> env11, tmp:tmp -> tmp25, tmp:tmp -> tmp26, tmp:tmp -> tmp27, tmp:inlinedVal -> inlinedVal3, tmp:tmp -> tmp67, tmp:tmp -> tmp68, tmp:block$res -> block$res9, tmp:tmp -> tmp28, tmp:tmp -> tmp69, tmp:scrut -> scrut3, tmp:tmp -> tmp70, member:Unify -> Unify1, tmp:block$res -> block$res20, tmp:tmp -> tmp71, pattern:Unify -> Unify, tmp:tmp -> tmp72, tmp:block$res -> block$res36, member:Env -> Env1, class:Env -> Env, tmp:tmp -> tmp73, tmp:tmp -> tmp74, member:Iter -> Iter, tmp:tmp -> tmp75, class:TVar -> TVar, env -> env8, member:instance$Ident(Gen) -> instance$Ident$_Gen$_8, tmp:tmp -> tmp76, tmp:tmp -> tmp77, tmp:inlinedVal -> inlinedVal12, tmp:block$res -> block$res37, class:TPrim -> TPrim, tmp:tmp -> tmp78, member:Runtime -> Runtime, tmp:tmp -> tmp79, tmp:tmp -> tmp80, env -> env9, member:instance$Ident(Gen) -> instance$Ident$_Gen$_9, tmp:tmp -> tmp81, tmp:tmp -> tmp82, tmp:inlinedVal -> inlinedVal13, tmp:block$res -> block$res38, env2 -> env21, tmp:tmp -> tmp83, tmp:tmp -> tmp84, tmp:tmp -> tmp85, tmp:tmp -> tmp86, tmp:block$res -> block$res39, tmp:block$res -> block$res3, tmp:tmp -> tmp87, TInt -> TInt, tmp:tmp -> tmp88, tmp:tmp -> tmp89, TBool -> TBool, tmp:tmp -> tmp90, tmp:tmp -> tmp91, tmp:block$res -> block$res4, env -> env10, member:Term -> Term2, member:IntLit -> IntLit1, member:instance$Ident(Gen) -> instance$Ident$_Gen$_10, member:Var -> Var1, tmp:tmp -> tmp92, member:App -> App1, tmp:tmp -> tmp93, member:Abs -> Abs1, tmp:inlinedVal -> inlinedVal14, member:BoolLit -> BoolLit1, member:ShowTerm -> ShowTerm1, tmp:block$res -> block$res40, pattern:ShowTerm -> ShowTerm, class:Abs -> Abs, tmp:tmp -> tmp94, tmp:tmp -> tmp95, tmp:tmp -> tmp96, tmp:tmp -> tmp97, tmp:tmp -> tmp98, env -> env12, class:App -> App, tmp:block$res -> block$res21, emptyEnv -> emptyEnv, member:instance$Ident(Gen) -> instance$Ident$_Gen$_11, tmp:tmp -> tmp99, tmp:tmp -> tmp29, tmp:tmp -> tmp100, tmp:block$res -> block$res22, tmp:inlinedVal -> inlinedVal15, tmp:block$res -> block$res41, member:Gen -> Gen1, env3 -> env31, class:Gen -> Gen, tmp:tmp -> tmp101, tmp:tmp -> tmp102, tmp:tmp -> tmp103, tmp:tmp -> tmp104, tmp:tmp -> tmp105, tmp:tmp -> tmp106, tmp:tmp -> tmp107, class:Term -> Term1, tmp:tmp -> tmp108, tmp:tmp -> tmp109, tmp:block$res -> block$res42, class:Var -> Var, tmp:tmp -> tmp110, env -> env13, member:instance$Ident(Gen) -> instance$Ident$_Gen$_12, tmp:tmp -> tmp111, tmp:tmp -> tmp112, tmp:inlinedVal -> inlinedVal16, tmp:block$res -> block$res43, tmp:block$res -> block$res23, class:IntLit -> IntLit, class:BoolLit -> BoolLit, member:lambda$ -> lambda$, member:inferTop -> inferTop, tmp:block$res -> block$res5, member:Scheme -> Scheme1, class:Scheme -> Scheme, tmp:block$res -> block$res24, tmp:block$res -> block$res10, member:unify' -> unify$_, member:inferType -> inferType, tmp:block$res -> block$res11, member:unify -> unify, tmp:block$res -> block$res25, id -> id, const -> const1, apply -> apply, tmp:block$res -> block$res6, compose -> compose, member:Subst -> Subst1, class:Subst -> Subst, tmp:tmp -> tmp30, tmp:tmp -> tmp31, tmp:tmp -> tmp32, tmp:tmp -> tmp33, tmp:tmp -> tmp34, tmp:tmp -> tmp35, tmp:tmp -> tmp36, tmp:tmp -> tmp37, tmp:tmp -> tmp38, tmp:tmp -> tmp39, tmp:tmp -> tmp40, tmp:tmp -> tmp41, tmp:tmp -> tmp42, tmp:tmp -> tmp43, tmp:block$res -> block$res26, tmp:block$res -> block$res27, env -> env, term -> term, member:instance$Ident(Gen) -> instance$Ident$_Gen$_, tmp:tmp -> tmp44, tmp:tmp -> tmp45, tmp:inlinedVal -> inlinedVal4, tmp:block$res -> block$res28, env -> env1)
-//│     defaultImportBindings = HashMap(/storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Iter.mjs -> Iter, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Option.mjs -> Option, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Runtime.mjs -> Runtime, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Predef.mjs -> Predef)
-//│ ═══[COMPILATION ERROR] No definition found in scope for member 'infer$tailrec'
-//│ FAILURE: Unexpected runtime error
-//│ FAILURE LOCATION: mkQuery (JSBackendDiffMaker.scala:259)
-//│ ═══[RUNTIME ERROR] ReferenceError: infer$tailrec is not defined
-//│     at REPL136:1:239
-//│     at ContextifyScript.runInThisContext (node:vm:138:12)
-//│     at defaultEval (node:repl:608:24)
-//│     at REPLEvalInContext (node:repl:691:9)
-//│     at AsyncLocalStorage.run (node:internal/async_local_storage/async_context_frame:66:14)
-//│     at REPLServer.REPLEval [as eval] (node:repl:690:19)
-//│     at REPLServer.onLine (node:repl:828:12)
-//│     at REPLServer.emit (node:events:514:20)
-//│     at [_onLine] [as _onLine] (node:internal/readline/interface:474:12)
-//│     at [_normalWrite] [as _normalWrite] (node:internal/readline/interface:669:18)
+//│ = "∀t₀. Bool -> t₀ -> t₀ -> t₀"
 
 :silent
 let t = App(App(App(Var("if"), BoolLit(true)), App(Var("id"), Var("id"))), Var("id"))
 print of t.show
 print of env3 |- t
-//│ FAILURE: Unexpected compilation error
-//│ FAILURE LOCATION: lookup_! (Scope.scala:136)
-//│ FAILURE INFO: Tuple2:
-//│   _1 = Tuple2:
-//│     _1 = member:infer$tailrec⁰
-//│     _2 = class hkmc2.semantics.BlockMemberSymbol
-//│   _2 = Scope:
-//│     parentOrCfg = Left of Cfg:
-//│       escapeChars = true
-//│       useSuperscripts = false
-//│       includeZero = false
-//│       defaultName = "tmp"
-//│     curThis = S of S of globalThis:globalThis⁰
-//│     bindings = HashMap(term -> term1, member:instance$Ident(Gen) -> instance$Ident$_Gen$_1, tmp:runtime -> runtime, tmp:block$res -> block$res12, tmp:tmp -> tmp46, tmp:definitionMetadata -> definitionMetadata, tmp:tmp -> tmp47, tmp:prettyPrint -> prettyPrint, tmp:inlinedVal -> inlinedVal5, tmp:Term -> Term, tmp:Block -> Block, tmp:tmp -> tmp1, tmp:block$res -> block$res29, tmp:option -> option, tmp:block$res -> block$res13, env -> env2, term -> term2, t1 -> t1, t2 -> t2, member:instance$Ident(Gen) -> instance$Ident$_Gen$_2, tmp:inlinedVal -> inlinedVal, tmp:tmp -> tmp48, tmp:tmp -> tmp49, tmp:tmp -> tmp2, tmp:inlinedVal -> inlinedVal6, tmp:scrut -> scrut, tmp:block$res -> block$res14, tmp:block$res -> block$res30, env -> env3, term -> term3, tmp:tmp -> tmp3, tmp:tmp -> tmp4, tmp:block$res -> block$res15, member:instance$Ident(Gen) -> instance$Ident$_Gen$_3, tmp:tmp -> tmp50, tmp:tmp -> tmp51, tmp:inlinedVal -> inlinedVal7, tmp:tmp -> tmp5, tmp:block$res -> block$res31, t2 -> t21, tmp:inlinedVal -> inlinedVal1, tmp:tmp -> tmp52, env -> env4, tmp:block$res -> block$res, tmp:tmp -> tmp6, tmp:scrut -> scrut1, tmp:block$res -> block$res1, tmp:block$res -> block$res16, member:instance$Ident(Gen) -> instance$Ident$_Gen$_4, tmp:block$res -> block$res2, tmp:tmp -> tmp53, tmp:tmp -> tmp54, tmp:inlinedVal -> inlinedVal8, member:Option -> Option, tmp:block$res -> block$res32, member:Type -> Type1, member:TVar -> TVar1, member:TFun -> TFun1, tmp:tmp -> tmp7, tmp:tmp -> tmp55, member:TPrim -> TPrim1, tmp:tmp -> tmp8, env -> env5, class:Type -> Type, tmp:tmp -> tmp9, tmp:tmp -> tmp10, tmp:tmp -> tmp11, tmp:tmp -> tmp12, member:instance$Ident(Gen) -> instance$Ident$_Gen$_5, class:TFun -> TFun, tmp:tmp -> tmp13, tmp:tmp -> tmp56, tmp:block$res -> block$res17, tmp:tmp -> tmp57, tmp:inlinedVal -> inlinedVal9, tmp:block$res -> block$res33, tmp:tmp -> tmp58, tmp:tmp -> tmp59, tmp:tmp -> tmp14, env -> env6, tmp:tmp -> tmp15, tmp:tmp -> tmp16, tmp:tmp -> tmp17, tmp:tmp -> tmp18, member:instance$Ident(Gen) -> instance$Ident$_Gen$_6, tmp:tmp -> tmp19, tmp:tmp -> tmp60, tmp:tmp -> tmp61, tmp:inlinedVal -> inlinedVal10, tmp:inlinedVal -> inlinedVal2, tmp:block$res -> block$res34, tmp:tmp -> tmp20, tmp:scrut -> scrut2, tmp:block$res -> block$res18, tmp:tmp -> tmp62, tmp:tmp -> tmp63, tmp:tmp -> tmp64, tmp:block$res -> block$res7, env -> env7, emptySub -> emptySub, tmp:tmp -> tmp21, tmp:tmp -> tmp22, tmp:tmp -> tmp23, member:instance$Ident(Gen) -> instance$Ident$_Gen$_7, tmp:tmp -> tmp, tmp:tmp -> tmp24, tmp:tmp -> tmp65, member:Predef -> Predef, tmp:block$res -> block$res8, tmp:block$res -> block$res19, tmp:tmp -> tmp66, tmp:inlinedVal -> inlinedVal11, member:applyPattern -> applyPattern, tmp:block$res -> block$res35, env1 -> env11, tmp:tmp -> tmp25, tmp:tmp -> tmp26, tmp:tmp -> tmp27, tmp:inlinedVal -> inlinedVal3, tmp:tmp -> tmp67, tmp:tmp -> tmp68, tmp:block$res -> block$res9, tmp:tmp -> tmp28, tmp:tmp -> tmp69, tmp:scrut -> scrut3, tmp:tmp -> tmp70, member:Unify -> Unify1, tmp:block$res -> block$res20, tmp:tmp -> tmp71, pattern:Unify -> Unify, tmp:tmp -> tmp72, tmp:block$res -> block$res36, member:Env -> Env1, class:Env -> Env, tmp:tmp -> tmp73, tmp:tmp -> tmp74, member:Iter -> Iter, tmp:tmp -> tmp75, class:TVar -> TVar, env -> env8, member:instance$Ident(Gen) -> instance$Ident$_Gen$_8, tmp:tmp -> tmp76, tmp:tmp -> tmp77, tmp:inlinedVal -> inlinedVal12, tmp:block$res -> block$res37, class:TPrim -> TPrim, tmp:tmp -> tmp78, member:Runtime -> Runtime, tmp:tmp -> tmp79, tmp:tmp -> tmp80, env -> env9, member:instance$Ident(Gen) -> instance$Ident$_Gen$_9, tmp:tmp -> tmp81, tmp:tmp -> tmp82, tmp:inlinedVal -> inlinedVal13, tmp:block$res -> block$res38, env2 -> env21, tmp:tmp -> tmp83, tmp:tmp -> tmp84, tmp:tmp -> tmp85, tmp:tmp -> tmp86, tmp:block$res -> block$res39, tmp:block$res -> block$res3, tmp:tmp -> tmp87, TInt -> TInt, tmp:tmp -> tmp88, tmp:tmp -> tmp89, TBool -> TBool, tmp:tmp -> tmp90, tmp:tmp -> tmp91, tmp:block$res -> block$res4, env -> env10, member:Term -> Term2, member:IntLit -> IntLit1, member:instance$Ident(Gen) -> instance$Ident$_Gen$_10, member:Var -> Var1, tmp:tmp -> tmp92, member:App -> App1, tmp:tmp -> tmp93, member:Abs -> Abs1, tmp:inlinedVal -> inlinedVal14, member:BoolLit -> BoolLit1, member:ShowTerm -> ShowTerm1, tmp:block$res -> block$res40, pattern:ShowTerm -> ShowTerm, class:Abs -> Abs, tmp:tmp -> tmp94, tmp:tmp -> tmp95, tmp:tmp -> tmp96, tmp:tmp -> tmp97, tmp:tmp -> tmp98, env -> env12, class:App -> App, tmp:block$res -> block$res21, emptyEnv -> emptyEnv, member:instance$Ident(Gen) -> instance$Ident$_Gen$_11, tmp:tmp -> tmp99, tmp:tmp -> tmp29, tmp:tmp -> tmp100, tmp:block$res -> block$res22, tmp:inlinedVal -> inlinedVal15, tmp:block$res -> block$res41, member:Gen -> Gen1, env3 -> env31, class:Gen -> Gen, tmp:tmp -> tmp101, tmp:tmp -> tmp102, tmp:tmp -> tmp103, tmp:tmp -> tmp104, tmp:tmp -> tmp105, tmp:tmp -> tmp106, tmp:tmp -> tmp107, class:Term -> Term1, tmp:tmp -> tmp108, tmp:tmp -> tmp109, tmp:block$res -> block$res42, class:Var -> Var, tmp:tmp -> tmp110, env -> env13, member:instance$Ident(Gen) -> instance$Ident$_Gen$_12, tmp:tmp -> tmp111, tmp:tmp -> tmp112, tmp:inlinedVal -> inlinedVal16, tmp:block$res -> block$res43, t -> t, tmp:block$res -> block$res23, class:IntLit -> IntLit, class:BoolLit -> BoolLit, tmp:tmp -> tmp113, tmp:tmp -> tmp114, tmp:tmp -> tmp115, tmp:tmp -> tmp116, tmp:tmp -> tmp117, tmp:tmp -> tmp118, tmp:tmp -> tmp119, tmp:tmp -> tmp120, env -> env14, term -> term4, tmp:inlinedVal -> inlinedVal17, member:instance$Ident(Gen) -> instance$Ident$_Gen$_13, tmp:tmp -> tmp121, tmp:tmp -> tmp122, tmp:inlinedVal -> inlinedVal18, tmp:block$res -> block$res44, member:lambda$ -> lambda$, member:inferTop -> inferTop, tmp:block$res -> block$res5, member:Scheme -> Scheme1, class:Scheme -> Scheme, tmp:block$res -> block$res24, tmp:block$res -> block$res10, member:unify' -> unify$_, member:inferType -> inferType, tmp:block$res -> block$res11, member:unify -> unify, tmp:block$res -> block$res25, id -> id, const -> const1, apply -> apply, tmp:block$res -> block$res6, compose -> compose, member:Subst -> Subst1, class:Subst -> Subst, tmp:tmp -> tmp30, tmp:tmp -> tmp31, tmp:tmp -> tmp32, tmp:tmp -> tmp33, tmp:tmp -> tmp34, tmp:tmp -> tmp35, tmp:tmp -> tmp36, tmp:tmp -> tmp37, tmp:tmp -> tmp38, tmp:tmp -> tmp39, tmp:tmp -> tmp40, tmp:tmp -> tmp41, tmp:tmp -> tmp42, tmp:tmp -> tmp43, tmp:block$res -> block$res26, tmp:block$res -> block$res27, env -> env, term -> term, member:instance$Ident(Gen) -> instance$Ident$_Gen$_, tmp:tmp -> tmp44, tmp:tmp -> tmp45, tmp:inlinedVal -> inlinedVal4, tmp:block$res -> block$res28, env -> env1)
-//│     defaultImportBindings = HashMap(/storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Iter.mjs -> Iter, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Option.mjs -> Option, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Runtime.mjs -> Runtime, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Predef.mjs -> Predef)
-//│ ═══[COMPILATION ERROR] No definition found in scope for member 'infer$tailrec'
 //│ > if true (id id) id
-//│ FAILURE: Unexpected runtime error
-//│ FAILURE LOCATION: mkQuery (JSBackendDiffMaker.scala:259)
-//│ ═══[RUNTIME ERROR] ReferenceError: infer$tailrec is not defined
-//│     at REPL139:1:762
-//│     at ContextifyScript.runInThisContext (node:vm:138:12)
-//│     at defaultEval (node:repl:608:24)
-//│     at REPLEvalInContext (node:repl:691:9)
-//│     at AsyncLocalStorage.run (node:internal/async_local_storage/async_context_frame:66:14)
-//│     at REPLServer.REPLEval [as eval] (node:repl:690:19)
-//│     at REPLServer.onLine (node:repl:828:12)
-//│     at REPLServer.emit (node:events:514:20)
-//│     at [_onLine] [as _onLine] (node:internal/readline/interface:474:12)
-//│     at [_normalWrite] [as _normalWrite] (node:internal/readline/interface:669:18)
+//│ > ∀t₆. t₆ -> t₆
 
 :silent
 :re
 let t = App(App(App(Var("if"), BoolLit(true)), App(Var("id"), Var("id"))), Var("add"))
 print of t.show
 print of env3 |- t
-//│ FAILURE: Unexpected compilation error
-//│ FAILURE LOCATION: lookup_! (Scope.scala:136)
-//│ FAILURE INFO: Tuple2:
-//│   _1 = Tuple2:
-//│     _1 = member:infer$tailrec⁰
-//│     _2 = class hkmc2.semantics.BlockMemberSymbol
-//│   _2 = Scope:
-//│     parentOrCfg = Left of Cfg:
-//│       escapeChars = true
-//│       useSuperscripts = false
-//│       includeZero = false
-//│       defaultName = "tmp"
-//│     curThis = S of S of globalThis:globalThis⁰
-//│     bindings = HashMap(term -> term1, member:instance$Ident(Gen) -> instance$Ident$_Gen$_1, tmp:runtime -> runtime, tmp:block$res -> block$res12, tmp:tmp -> tmp46, tmp:definitionMetadata -> definitionMetadata, tmp:tmp -> tmp47, tmp:prettyPrint -> prettyPrint, tmp:inlinedVal -> inlinedVal5, tmp:Term -> Term, tmp:Block -> Block, tmp:tmp -> tmp1, tmp:block$res -> block$res29, tmp:option -> option, tmp:block$res -> block$res13, env -> env2, term -> term2, t1 -> t1, t2 -> t2, member:instance$Ident(Gen) -> instance$Ident$_Gen$_2, tmp:inlinedVal -> inlinedVal, tmp:tmp -> tmp48, tmp:tmp -> tmp49, tmp:tmp -> tmp2, tmp:inlinedVal -> inlinedVal6, tmp:scrut -> scrut, tmp:block$res -> block$res14, tmp:block$res -> block$res30, env -> env3, term -> term3, tmp:tmp -> tmp3, tmp:tmp -> tmp4, tmp:block$res -> block$res15, member:instance$Ident(Gen) -> instance$Ident$_Gen$_3, tmp:tmp -> tmp50, tmp:tmp -> tmp51, tmp:inlinedVal -> inlinedVal7, tmp:tmp -> tmp5, tmp:block$res -> block$res31, t2 -> t21, tmp:inlinedVal -> inlinedVal1, tmp:tmp -> tmp52, env -> env4, tmp:block$res -> block$res, tmp:tmp -> tmp6, tmp:scrut -> scrut1, tmp:block$res -> block$res1, tmp:block$res -> block$res16, member:instance$Ident(Gen) -> instance$Ident$_Gen$_4, tmp:block$res -> block$res2, tmp:tmp -> tmp53, tmp:tmp -> tmp54, tmp:inlinedVal -> inlinedVal8, member:Option -> Option, tmp:block$res -> block$res32, member:Type -> Type1, member:TVar -> TVar1, member:TFun -> TFun1, tmp:tmp -> tmp7, tmp:tmp -> tmp55, member:TPrim -> TPrim1, tmp:tmp -> tmp8, env -> env5, class:Type -> Type, tmp:tmp -> tmp9, tmp:tmp -> tmp10, tmp:tmp -> tmp11, tmp:tmp -> tmp12, member:instance$Ident(Gen) -> instance$Ident$_Gen$_5, class:TFun -> TFun, tmp:tmp -> tmp13, tmp:tmp -> tmp56, tmp:block$res -> block$res17, tmp:tmp -> tmp57, tmp:inlinedVal -> inlinedVal9, tmp:block$res -> block$res33, tmp:tmp -> tmp58, tmp:tmp -> tmp59, tmp:tmp -> tmp14, env -> env6, tmp:tmp -> tmp15, tmp:tmp -> tmp16, tmp:tmp -> tmp17, tmp:tmp -> tmp18, member:instance$Ident(Gen) -> instance$Ident$_Gen$_6, tmp:tmp -> tmp19, tmp:tmp -> tmp60, tmp:tmp -> tmp61, tmp:inlinedVal -> inlinedVal10, tmp:inlinedVal -> inlinedVal2, tmp:block$res -> block$res34, tmp:tmp -> tmp20, tmp:scrut -> scrut2, tmp:block$res -> block$res18, tmp:tmp -> tmp62, tmp:tmp -> tmp63, tmp:tmp -> tmp64, tmp:block$res -> block$res7, env -> env7, emptySub -> emptySub, tmp:tmp -> tmp21, tmp:tmp -> tmp22, tmp:tmp -> tmp23, member:instance$Ident(Gen) -> instance$Ident$_Gen$_7, tmp:tmp -> tmp, tmp:tmp -> tmp24, tmp:tmp -> tmp65, member:Predef -> Predef, tmp:block$res -> block$res8, tmp:block$res -> block$res19, tmp:tmp -> tmp66, tmp:inlinedVal -> inlinedVal11, member:applyPattern -> applyPattern, tmp:block$res -> block$res35, env1 -> env11, tmp:tmp -> tmp25, tmp:tmp -> tmp26, tmp:tmp -> tmp27, tmp:inlinedVal -> inlinedVal3, tmp:tmp -> tmp67, tmp:tmp -> tmp68, tmp:block$res -> block$res9, tmp:tmp -> tmp28, tmp:tmp -> tmp69, tmp:scrut -> scrut3, tmp:tmp -> tmp70, member:Unify -> Unify1, tmp:block$res -> block$res20, tmp:tmp -> tmp71, pattern:Unify -> Unify, tmp:tmp -> tmp72, tmp:block$res -> block$res36, member:Env -> Env1, class:Env -> Env, tmp:tmp -> tmp73, tmp:tmp -> tmp74, member:Iter -> Iter, tmp:tmp -> tmp75, class:TVar -> TVar, env -> env8, member:instance$Ident(Gen) -> instance$Ident$_Gen$_8, tmp:tmp -> tmp76, tmp:tmp -> tmp77, tmp:inlinedVal -> inlinedVal12, tmp:block$res -> block$res37, class:TPrim -> TPrim, tmp:tmp -> tmp78, member:Runtime -> Runtime, tmp:tmp -> tmp79, tmp:tmp -> tmp80, env -> env9, member:instance$Ident(Gen) -> instance$Ident$_Gen$_9, tmp:tmp -> tmp81, tmp:tmp -> tmp82, tmp:inlinedVal -> inlinedVal13, tmp:block$res -> block$res38, env2 -> env21, tmp:tmp -> tmp83, tmp:tmp -> tmp84, tmp:tmp -> tmp85, tmp:tmp -> tmp86, tmp:block$res -> block$res39, tmp:block$res -> block$res3, tmp:tmp -> tmp87, TInt -> TInt, tmp:tmp -> tmp88, tmp:tmp -> tmp89, TBool -> TBool, tmp:tmp -> tmp90, tmp:tmp -> tmp91, tmp:block$res -> block$res4, env -> env10, member:Term -> Term2, member:IntLit -> IntLit1, member:instance$Ident(Gen) -> instance$Ident$_Gen$_10, member:Var -> Var1, tmp:tmp -> tmp92, member:App -> App1, tmp:tmp -> tmp93, member:Abs -> Abs1, tmp:inlinedVal -> inlinedVal14, member:BoolLit -> BoolLit1, member:ShowTerm -> ShowTerm1, tmp:block$res -> block$res40, pattern:ShowTerm -> ShowTerm, class:Abs -> Abs, tmp:tmp -> tmp94, tmp:tmp -> tmp95, tmp:tmp -> tmp96, tmp:tmp -> tmp97, tmp:tmp -> tmp98, env -> env12, class:App -> App, tmp:block$res -> block$res21, emptyEnv -> emptyEnv, member:instance$Ident(Gen) -> instance$Ident$_Gen$_11, tmp:tmp -> tmp99, tmp:tmp -> tmp29, tmp:tmp -> tmp100, tmp:block$res -> block$res22, tmp:inlinedVal -> inlinedVal15, tmp:block$res -> block$res41, member:Gen -> Gen1, env3 -> env31, class:Gen -> Gen, tmp:tmp -> tmp101, tmp:tmp -> tmp102, tmp:tmp -> tmp103, tmp:tmp -> tmp104, tmp:tmp -> tmp105, tmp:tmp -> tmp106, tmp:tmp -> tmp107, class:Term -> Term1, tmp:tmp -> tmp108, tmp:tmp -> tmp109, tmp:block$res -> block$res42, class:Var -> Var, tmp:tmp -> tmp110, env -> env13, member:instance$Ident(Gen) -> instance$Ident$_Gen$_12, tmp:tmp -> tmp111, tmp:tmp -> tmp112, tmp:inlinedVal -> inlinedVal16, tmp:block$res -> block$res43, t -> t, tmp:block$res -> block$res23, class:IntLit -> IntLit, class:BoolLit -> BoolLit, tmp:tmp -> tmp113, tmp:tmp -> tmp114, tmp:tmp -> tmp115, tmp:tmp -> tmp116, tmp:tmp -> tmp117, tmp:tmp -> tmp118, tmp:tmp -> tmp119, tmp:tmp -> tmp120, env -> env14, term -> term4, tmp:inlinedVal -> inlinedVal17, member:instance$Ident(Gen) -> instance$Ident$_Gen$_13, tmp:tmp -> tmp121, tmp:tmp -> tmp122, tmp:inlinedVal -> inlinedVal18, tmp:block$res -> block$res44, t -> t3, member:lambda$ -> lambda$, tmp:tmp -> tmp123, tmp:tmp -> tmp124, tmp:tmp -> tmp125, tmp:tmp -> tmp126, tmp:tmp -> tmp127, tmp:tmp -> tmp128, tmp:tmp -> tmp129, tmp:tmp -> tmp130, env -> env15, term -> term5, tmp:inlinedVal -> inlinedVal19, member:instance$Ident(Gen) -> instance$Ident$_Gen$_14, tmp:tmp -> tmp131, tmp:tmp -> tmp132, tmp:inlinedVal -> inlinedVal20, tmp:block$res -> block$res45, member:inferTop -> inferTop, tmp:block$res -> block$res5, member:Scheme -> Scheme1, class:Scheme -> Scheme, tmp:block$res -> block$res24, tmp:block$res -> block$res10, member:unify' -> unify$_, member:inferType -> inferType, tmp:block$res -> block$res11, member:unify -> unify, tmp:block$res -> block$res25, id -> id, const -> const1, apply -> apply, tmp:block$res -> block$res6, compose -> compose, member:Subst -> Subst1, class:Subst -> Subst, tmp:tmp -> tmp30, tmp:tmp -> tmp31, tmp:tmp -> tmp32, tmp:tmp -> tmp33, tmp:tmp -> tmp34, tmp:tmp -> tmp35, tmp:tmp -> tmp36, tmp:tmp -> tmp37, tmp:tmp -> tmp38, tmp:tmp -> tmp39, tmp:tmp -> tmp40, tmp:tmp -> tmp41, tmp:tmp -> tmp42, tmp:tmp -> tmp43, tmp:block$res -> block$res26, tmp:block$res -> block$res27, env -> env, term -> term, member:instance$Ident(Gen) -> instance$Ident$_Gen$_, tmp:tmp -> tmp44, tmp:tmp -> tmp45, tmp:inlinedVal -> inlinedVal4, tmp:block$res -> block$res28, env -> env1)
-//│     defaultImportBindings = HashMap(/storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Iter.mjs -> Iter, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Option.mjs -> Option, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Runtime.mjs -> Runtime, /storage/mark/Repos/mlscript/hkmc2/shared/src/test/mlscript-compile/Predef.mjs -> Predef)
-//│ ═══[COMPILATION ERROR] No definition found in scope for member 'infer$tailrec'
 //│ > if true (id id) add
-//│ ═══[RUNTIME ERROR] ReferenceError: infer$tailrec is not defined
+//│ ═══[RUNTIME ERROR] Error: Cannot unify Int with Int -> Int

From 1dcd822735e1c9c0af3dae01f5110227cdc2f283 Mon Sep 17 00:00:00 2001
From: CAG2Mark <git@markng.com>
Date: Thu, 27 Aug 2026 17:16:37 +0800
Subject: [PATCH 07/13] make wrapper private

---
 .../main/scala/hkmc2/codegen/TailRecOpt.scala |  2 +-
 .../test/mlscript/tailrec/MultiArgLists.mls   | 43 ++++++++-----------
 .../src/test/mlscript/tailrec/TailRecOpt.mls  | 29 +++++++------
 3 files changed, 35 insertions(+), 39 deletions(-)

diff --git a/hkmc2/shared/src/main/scala/hkmc2/codegen/TailRecOpt.scala b/hkmc2/shared/src/main/scala/hkmc2/codegen/TailRecOpt.scala
index 3f643eeb17..41125bd45d 100644
--- a/hkmc2/shared/src/main/scala/hkmc2/codegen/TailRecOpt.scala
+++ b/hkmc2/shared/src/main/scala/hkmc2/codegen/TailRecOpt.scala
@@ -605,7 +605,7 @@ class TailRecOpt(checkAnnotations: Bool)(using State, TL, Raise):
       val loopDefn = FunDefn(
         owner, bms, dSym,
         newParamLists,
-        loop)(N, annotations = Nil) // Q: maybe should be Private?
+        loop)(N, annotations = Annot.Private :: Nil)
       (S(loopDefn), wrappers)
   
   def optFunctions(fs: List[FunDefn], owner: Opt[InnerSymbol])(using (ScopeData, AccessMap)) =
diff --git a/hkmc2/shared/src/test/mlscript/tailrec/MultiArgLists.mls b/hkmc2/shared/src/test/mlscript/tailrec/MultiArgLists.mls
index 5bbceb2fc3..e869e1248a 100644
--- a/hkmc2/shared/src/test/mlscript/tailrec/MultiArgLists.mls
+++ b/hkmc2/shared/src/test/mlscript/tailrec/MultiArgLists.mls
@@ -20,6 +20,7 @@ fun loop(x)(y) =
 loop(1000)(0)
 //│ ——————————————| Optimized IR |——————————————————————————————————————————————————————————————————————
 //│ let loop$tailrec;
+//│ @private
 //│ define loop$tailrec as fun loop$tailrec⁰(x, y) {
 //│   loop loopLabel:
 //│     let scrut, tmp, tmp1;
@@ -51,6 +52,7 @@ fun count(start)(stop) =
 count(0)(100)
 //│ ——————————————| Optimized IR |——————————————————————————————————————————————————————————————————————
 //│ let count$tailrec, start, stop, inlinedVal;
+//│ @private
 //│ define count$tailrec as fun count$tailrec⁰(start1, stop1) {
 //│   loop loopLabel:
 //│     let scrut, tmp;
@@ -95,6 +97,7 @@ fun even(n)(dummy) = if n == 0 then [true, dummy] else odd(n - 1)(dummy + 1)
 fun odd(n)(dummy) = if n == 0 then [false, dummy] else even(n - 1)(dummy + 1)
 //│ ——————————————| Optimized IR |——————————————————————————————————————————————————————————————————————
 //│ let even_odd;
+//│ @private
 //│ define even_odd as fun even_odd⁰(id, param0, param1) {
 //│   loop loopLabel:
 //│     match id
@@ -167,7 +170,8 @@ fun handleEffect(x) =
 fun resume(x)(y) = handleEffects(x)
 //│ ——————————————| Optimized IR |——————————————————————————————————————————————————————————————————————
 //│ let handleEffects_handleEffect;
-//│ define handleEffects_handleEffect as fun handleEffects_handleEffect⁰(id, param0) {
+//│ @private
+//│ define handleEffects_handleEffect as fun handleEffects_handleEffect⁰(id) {
 //│   loop loopLabel:
 //│     match id
 //│       0 =>
@@ -175,7 +179,7 @@ fun resume(x)(y) = handleEffects(x)
 //│         continue loopLabel
 //│       1 =>
 //│         let tmp;
-//│         set tmp = resume⁰(param0);
+//│         set tmp = resume⁰(undefined);
 //│         do sink⁰.push﹖(tmp);
 //│         set id = 0;
 //│         continue loopLabel
@@ -185,10 +189,10 @@ fun resume(x)(y) = handleEffects(x)
 //│   end
 //│ };
 //│ define handleEffects⁰ as fun handleEffects¹(x) {
-//│   return handleEffects_handleEffect⁰(0, x)
+//│   return handleEffects_handleEffect⁰(0)
 //│ };
 //│ define handleEffect⁰ as fun handleEffect¹(x) {
-//│   return handleEffects_handleEffect⁰(1, x)
+//│   return handleEffects_handleEffect⁰(1)
 //│ };
 //│ @inline
 //│ define resume¹ as fun resume⁰(x)(y) { return handleEffects¹(x) };
@@ -209,7 +213,8 @@ fun g(n)(m) =
   @tailcall f(n - 1)(...[1, 2], 3, ...[3, 4], ...[5, n], 7, n)(m)
 //│ ——————————————| Optimized IR |——————————————————————————————————————————————————————————————————————
 //│ let f_g;
-//│ define f_g as fun f_g⁰(id, param0, param1, param2, param3, param4, param5, param6) {
+//│ @private
+//│ define f_g as fun f_g⁰(id, param0, param1, param5, param6) {
 //│   loop loopLabel:
 //│     match id
 //│       0 =>
@@ -250,12 +255,10 @@ fun g(n)(m) =
 //│   end
 //│ };
 //│ define f⁰ as fun f¹(n)(a, b, c, d, ...e)(m) {
-//│   return f_g⁰(0, n, a, b, c, d, e, m)
+//│   return f_g⁰(0, n, a, e, m)
 //│ };
 //│ @inline
-//│ define g⁰ as fun g¹(n)(m) {
-//│   return f_g⁰(1, n, m, undefined, undefined, undefined, undefined, undefined)
-//│ };
+//│ define g⁰ as fun g¹(n)(m) { return f_g⁰(1, n, m, undefined, undefined) };
 //│ end
 //│ —————————————————| Output |—————————————————————————————————————————————————————————————————————————
 
@@ -314,14 +317,7 @@ fun f(a)(b) = f(a)(b)
 //│         sym = member:f$tailrec⁰
 //│         dSym = term:f$tailrec¹
 //│         params = Ls of
-//│           ParamList:
-//│             params = Ls of
-//│               Param:
-//│                 sym = a⁰
-//│                 modulefulness = Modulefulness of N
-//│               Param:
-//│                 sym = b⁰
-//│                 modulefulness = Modulefulness of N
+//│           ParamList: ‹empty›
 //│         body = Label:
 //│           label = label:loopLabel⁰
 //│           loop = true
@@ -335,23 +331,19 @@ fun f(a)(b) = f(a)(b)
 //│           ParamList:
 //│             params = Ls of
 //│               Param:
-//│                 sym = a¹
+//│                 sym = a⁰
 //│                 modulefulness = Modulefulness of N
 //│           ParamList:
 //│             params = Ls of
 //│               Param:
-//│                 sym = b¹
+//│                 sym = b⁰
 //│                 modulefulness = Modulefulness of N
 //│         body = Return of Call:
 //│           fun = MemberRef{disamb=term:f$tailrec¹}:
 //│             bms = member:f$tailrec⁰
 //│             disamb = term:f$tailrec¹
 //│           argss = Ls of
-//│             Ls of
-//│               Arg:
-//│                 value = SimpleRef of a¹
-//│               Arg:
-//│                 value = SimpleRef of b¹
+//│             Nil
 //│ —————————————————| Output |—————————————————————————————————————————————————————————————————————————
 
 
@@ -364,6 +356,7 @@ fun loop(x)(y) =
 fun f = loop(1000)(0)
 //│ ——————————————| Optimized IR |——————————————————————————————————————————————————————————————————————
 //│ let loop$tailrec;
+//│ @private
 //│ define loop$tailrec as fun loop$tailrec¹(x, y) {
 //│   loop loopLabel:
 //│     let scrut, tmp, tmp1;
@@ -397,6 +390,7 @@ fun loop(x)(y) =
 loop(5)(5)
 //│ ——————————————| Optimized IR |——————————————————————————————————————————————————————————————————————
 //│ let loop$tailrec;
+//│ @private
 //│ define loop$tailrec as fun loop$tailrec²(x, y) {
 //│   loop loopLabel:
 //│     let scrut, scrut1, tmp, tmp1, tmp2;
@@ -457,6 +451,7 @@ fun f(n)(a)(...z) =
       res
 //│ ——————————————| Optimized IR |——————————————————————————————————————————————————————————————————————
 //│ let f$tailrec;
+//│ @private
 //│ define f$tailrec as fun f$tailrec²(n, a, z) {
 //│   loop loopLabel:
 //│     let scrut, res, tmp, tmp1;
diff --git a/hkmc2/shared/src/test/mlscript/tailrec/TailRecOpt.mls b/hkmc2/shared/src/test/mlscript/tailrec/TailRecOpt.mls
index e42a8f9a81..6faa4adefa 100644
--- a/hkmc2/shared/src/test/mlscript/tailrec/TailRecOpt.mls
+++ b/hkmc2/shared/src/test/mlscript/tailrec/TailRecOpt.mls
@@ -19,6 +19,7 @@ fun f(a, b, c) =
 f(10000, 20000, 0)
 //│ ——————————————| Optimized IR |——————————————————————————————————————————————————————————————————————
 //│ let g_f;
+//│ @private
 //│ define g_f as fun g_f⁰(id, param0, param1, param2, param3) {
 //│   loop loopLabel:
 //│     match id
@@ -152,7 +153,8 @@ fun g(n) =
   @tailcall f(n, ...[1, 2], 3, ...[3, 4], ...[5, n], 7, n)
 //│ ——————————————| Optimized IR |——————————————————————————————————————————————————————————————————————
 //│ let f_g;
-//│ define f_g as fun f_g⁰(id, param0, param1, param2, param3, param4, param5) {
+//│ @private
+//│ define f_g as fun f_g⁰(id, param0, param5) {
 //│   loop loopLabel:
 //│     match id
 //│       0 =>
@@ -189,11 +191,9 @@ fun g(n) =
 //│   end
 //│ };
 //│ define f² as fun f³(n, a, b, c, d, ...e) {
-//│   return f_g⁰(0, n, a, b, c, d, e)
-//│ };
-//│ define g² as fun g³(n) {
-//│   return f_g⁰(1, n, undefined, undefined, undefined, undefined, undefined)
+//│   return f_g⁰(0, n, e)
 //│ };
+//│ define g² as fun g³(n) { return f_g⁰(1, n, undefined) };
 //│ end
 //│ —————————————————| Output |—————————————————————————————————————————————————————————————————————————
 
@@ -304,22 +304,23 @@ fun g(x) =
   0
 //│ ——————————————| Optimized IR |——————————————————————————————————————————————————————————————————————
 //│ let f_g;
-//│ define f_g as fun f_g¹(id, param0) {
+//│ @private
+//│ define f_g as fun f_g¹(id) {
 //│   loop loopLabel:
 //│     match id
 //│       0 =>
 //│         set id = 1;
 //│         continue loopLabel
 //│       1 =>
-//│         do f_g¹(0, param0);
+//│         do f_g¹(0);
 //│         return 0
 //│       else
 //│         end
 //│     end
 //│   end
 //│ };
-//│ define f⁶ as fun f⁷(x) { return f_g¹(0, x) };
-//│ define g⁴ as fun g⁵(x) { return f_g¹(1, x) };
+//│ define f⁶ as fun f⁷(x) { return f_g¹(0) };
+//│ define g⁴ as fun g⁵(x) { return f_g¹(1) };
 //│ end
 //│ —————————————————| Output |—————————————————————————————————————————————————————————————————————————
 
@@ -362,10 +363,10 @@ module A with
     @tailcall g(x - 1)
 A.f(10000)
 //│ ╔══[COMPILATION ERROR] This tail call exits the current scope and is not optimized.
-//│ ║  l.361: 	    fun g(x) = if x < 0 then 0 else @tailcall f(x)
+//│ ║  l.362: 	    fun g(x) = if x < 0 then 0 else @tailcall f(x)
 //│ ╙──       	                                              ^^^^
 //│ ╔══[COMPILATION ERROR] This tail call exits the current scope and is not optimized.
-//│ ║  l.362: 	    @tailcall g(x - 1)
+//│ ║  l.363: 	    @tailcall g(x - 1)
 //│ ╙──       	              ^^^^^^^^
 //│ = 0
 
@@ -392,12 +393,12 @@ class A with
   fun g(x) = if x == 0 then 1 else @tailcall f(x - 1)
 (new A).f(10)
 //│ ╔══[COMPILATION ERROR] Calls from class methods cannot yet be marked @tailcall.
-//│ ║  l.391: 	  @tailrec fun f(x) = if x == 0 then 0 else @tailcall g(x - 1)
+//│ ║  l.392: 	  @tailrec fun f(x) = if x == 0 then 0 else @tailcall g(x - 1)
 //│ ╙──       	                                                      ^^^^^^^^
 //│ ╔══[COMPILATION ERROR] Class methods may not yet be marked @tailrec.
-//│ ║  l.391: 	  @tailrec fun f(x) = if x == 0 then 0 else @tailcall g(x - 1)
+//│ ║  l.392: 	  @tailrec fun f(x) = if x == 0 then 0 else @tailcall g(x - 1)
 //│ ╙──       	               ^
 //│ ╔══[COMPILATION ERROR] Calls from class methods cannot yet be marked @tailcall.
-//│ ║  l.392: 	  fun g(x) = if x == 0 then 1 else @tailcall f(x - 1)
+//│ ║  l.393: 	  fun g(x) = if x == 0 then 1 else @tailcall f(x - 1)
 //│ ╙──       	                                             ^^^^^^^^
 //│ = 0

From 0f09d301c9b2c7bf1e0336a838749ec1c0644611 Mon Sep 17 00:00:00 2001
From: CAG2Mark <git@markng.com>
Date: Thu, 27 Aug 2026 21:19:04 +0800
Subject: [PATCH 08/13] add back inline annotation

---
 .../main/scala/hkmc2/codegen/TailRecOpt.scala |   8 +-
 .../test/mlscript/tailrec/MultiArgLists.mls   | 144 +++++++++++-------
 .../src/test/mlscript/tailrec/TailRecOpt.mls  |  18 ++-
 3 files changed, 103 insertions(+), 67 deletions(-)

diff --git a/hkmc2/shared/src/main/scala/hkmc2/codegen/TailRecOpt.scala b/hkmc2/shared/src/main/scala/hkmc2/codegen/TailRecOpt.scala
index 41125bd45d..2b8e7dfe29 100644
--- a/hkmc2/shared/src/main/scala/hkmc2/codegen/TailRecOpt.scala
+++ b/hkmc2/shared/src/main/scala/hkmc2/codegen/TailRecOpt.scala
@@ -595,17 +595,21 @@ class TailRecOpt(checkAnnotations: Bool)(using State, TL, Raise):
         val newBod = Return(
           rewriteKnownCall(f, paramArgs),
         )
-        FunDefn(f.owner, f.sym, f.dSym, f.params, newBod)(N, f.annotations)
+        val annots = if f.inline then f.annotations else Annot.Inline :: f.annotations 
+        FunDefn(f.owner, f.sym, f.dSym, f.params, newBod)(N, annots)
       val newParamLists =
         val initial = paramSyms.map(Param.simple(_))
         if funsLen > 1 then
           PlainParamList(Param.simple(curIdSym) :: initial) :: Nil
         else
           PlainParamList(initial) :: Nil
+      val annotations = 
+        if funsLen == 1 && funs.head.inline then Annot.Inline :: Annot.Private :: Nil
+        else Annot.Private :: Nil
       val loopDefn = FunDefn(
         owner, bms, dSym,
         newParamLists,
-        loop)(N, annotations = Annot.Private :: Nil)
+        loop)(N, annotations = annotations)
       (S(loopDefn), wrappers)
   
   def optFunctions(fs: List[FunDefn], owner: Opt[InnerSymbol])(using (ScopeData, AccessMap)) =
diff --git a/hkmc2/shared/src/test/mlscript/tailrec/MultiArgLists.mls b/hkmc2/shared/src/test/mlscript/tailrec/MultiArgLists.mls
index e869e1248a..19ffbc2191 100644
--- a/hkmc2/shared/src/test/mlscript/tailrec/MultiArgLists.mls
+++ b/hkmc2/shared/src/test/mlscript/tailrec/MultiArgLists.mls
@@ -188,14 +188,18 @@ fun resume(x)(y) = handleEffects(x)
 //│     end
 //│   end
 //│ };
+//│ @inline
 //│ define handleEffects⁰ as fun handleEffects¹(x) {
 //│   return handleEffects_handleEffect⁰(0)
 //│ };
+//│ @inline
 //│ define handleEffect⁰ as fun handleEffect¹(x) {
 //│   return handleEffects_handleEffect⁰(1)
 //│ };
 //│ @inline
-//│ define resume¹ as fun resume⁰(x)(y) { return handleEffects¹(x) };
+//│ define resume¹ as fun resume⁰(x)(y) {
+//│   return handleEffects_handleEffect⁰(0)
+//│ };
 //│ set sink⁰ = mut [];
 //│ end
 //│ —————————————————| Output |—————————————————————————————————————————————————————————————————————————
@@ -254,6 +258,7 @@ fun g(n)(m) =
 //│     end
 //│   end
 //│ };
+//│ @inline
 //│ define f⁰ as fun f¹(n)(a, b, c, d, ...e)(m) {
 //│   return f_g⁰(0, n, a, e, m)
 //│ };
@@ -271,32 +276,30 @@ fun f(a)(...z) = if z is
   [] then a
   [x, ...xs] then f(a + 1)(...xs)
 //│ ——————————————| Optimized IR |——————————————————————————————————————————————————————————————————————
-//│ define f² as fun f³(a)(...z) {
-//│   let a1, z1, inlinedVal;
-//│   set a1 = a;
-//│   set z1 = z;
-//│   block inlinedLbl:
-//│     loop loopLabel:
-//│       let tmp;
-//│       match z1
-//│         Array(0) =>
-//│           set inlinedVal = a1;
-//│           break inlinedLbl
-//│         Array(1+) =>
-//│           let inlinedVal1, tmp1;
-//│           do runtime⁰.Tuple⁰.get⁰(z1, 0);
-//│           set tmp1 = -¹(z1.length﹖, 0);
-//│           set inlinedVal1 = z1.slice﹖(1, tmp1);
-//│           set tmp = +⁰(a1, 1);
-//│           set a1 = tmp;
-//│           set z1 = inlinedVal1;
-//│           continue loopLabel
-//│         else
-//│           throw new globalThis⁰.Error⁰("match error")
-//│       end
-//│     unreachable /* Rest of abortive labelled block */
-//│   return inlinedVal
+//│ let f$tailrec;
+//│ @private
+//│ define f$tailrec as fun f$tailrec⁰(a, z) {
+//│   loop loopLabel:
+//│     let tmp;
+//│     match z
+//│       Array(0) =>
+//│         return a
+//│       Array(1+) =>
+//│         let inlinedVal, tmp1;
+//│         do runtime⁰.Tuple⁰.get⁰(z, 0);
+//│         set tmp1 = -¹(z.length﹖, 0);
+//│         set inlinedVal = z.slice﹖(1, tmp1);
+//│         set tmp = +⁰(a, 1);
+//│         set a = tmp;
+//│         set z = inlinedVal;
+//│         continue loopLabel
+//│       else
+//│         throw new globalThis⁰.Error⁰("match error")
+//│     end
+//│   unreachable /* Rest of abortive labelled block */
 //│ };
+//│ @inline
+//│ define f² as fun f³(a)(...z) { return f$tailrec⁰(a, z) };
 //│ end
 //│ —————————————————| Output |—————————————————————————————————————————————————————————————————————————
 
@@ -311,11 +314,11 @@ f(0)(1, 2, 3, 4)
 fun f(a)(b) = f(a)(b)
 //│ ————————————| Optimized IR Tree |———————————————————————————————————————————————————————————————————
 //│ Program:
-//│   main = Scoped(syms = {member:f$tailrec⁰}):
+//│   main = Scoped(syms = {member:f$tailrec¹}):
 //│     body = Define:
 //│       defn = FunDefn:
-//│         sym = member:f$tailrec⁰
-//│         dSym = term:f$tailrec¹
+//│         sym = member:f$tailrec¹
+//│         dSym = term:f$tailrec²
 //│         params = Ls of
 //│           ParamList: ‹empty›
 //│         body = Label:
@@ -339,9 +342,9 @@ fun f(a)(b) = f(a)(b)
 //│                 sym = b⁰
 //│                 modulefulness = Modulefulness of N
 //│         body = Return of Call:
-//│           fun = MemberRef{disamb=term:f$tailrec¹}:
-//│             bms = member:f$tailrec⁰
-//│             disamb = term:f$tailrec¹
+//│           fun = MemberRef{disamb=term:f$tailrec²}:
+//│             bms = member:f$tailrec¹
+//│             disamb = term:f$tailrec²
 //│           argss = Ls of
 //│             Nil
 //│ —————————————————| Output |—————————————————————————————————————————————————————————————————————————
@@ -355,29 +358,51 @@ fun loop(x)(y) =
   else loop(x - 1)(y + x)
 fun f = loop(1000)(0)
 //│ ——————————————| Optimized IR |——————————————————————————————————————————————————————————————————————
-//│ let loop$tailrec;
-//│ @private
-//│ define loop$tailrec as fun loop$tailrec¹(x, y) {
-//│   loop loopLabel:
-//│     let scrut, tmp, tmp1;
-//│     set scrut = Predef⁰.equals⁰(x, 0);
-//│     match scrut
-//│       true =>
-//│         return y
-//│       else
-//│         set tmp = -⁰(x, 1);
-//│         set tmp1 = +⁰(y, x);
-//│         set x = tmp;
-//│         set y = tmp1;
-//│         continue loopLabel
-//│     end
-//│   unreachable /* Rest of abortive labelled block */
-//│ };
 //│ @tailrec @inline
 //│ define loop² as fun loop³(x)(y) {
-//│   return loop$tailrec¹(x, y)
+//│   let x1, y1, inlinedVal;
+//│   set x1 = x;
+//│   set y1 = y;
+//│   block inlinedLbl:
+//│     loop loopLabel:
+//│       let scrut, tmp, tmp1;
+//│       set scrut = Predef⁰.equals⁰(x1, 0);
+//│       match scrut
+//│         true =>
+//│           set inlinedVal = y1;
+//│           break inlinedLbl
+//│         else
+//│           set tmp = -⁰(x1, 1);
+//│           set tmp1 = +⁰(y1, x1);
+//│           set x1 = tmp;
+//│           set y1 = tmp1;
+//│           continue loopLabel
+//│       end
+//│     unreachable /* Rest of abortive labelled block */
+//│   return inlinedVal
+//│ };
+//│ define f⁶ as fun f⁷() {
+//│   let x, y, inlinedVal;
+//│   set x = 1000;
+//│   set y = 0;
+//│   block inlinedLbl:
+//│     loop loopLabel:
+//│       let scrut, tmp, tmp1;
+//│       set scrut = Predef⁰.equals⁰(x, 0);
+//│       match scrut
+//│         true =>
+//│           set inlinedVal = y;
+//│           break inlinedLbl
+//│         else
+//│           set tmp = -⁰(x, 1);
+//│           set tmp1 = +⁰(y, x);
+//│           set x = tmp;
+//│           set y = tmp1;
+//│           continue loopLabel
+//│       end
+//│     unreachable /* Rest of abortive labelled block */
+//│   return inlinedVal
 //│ };
-//│ define f⁶ as fun f⁷() { return loop$tailrec¹(1000, 0) };
 //│ end
 //│ —————————————————| Output |—————————————————————————————————————————————————————————————————————————
 
@@ -391,7 +416,7 @@ loop(5)(5)
 //│ ——————————————| Optimized IR |——————————————————————————————————————————————————————————————————————
 //│ let loop$tailrec;
 //│ @private
-//│ define loop$tailrec as fun loop$tailrec²(x, y) {
+//│ define loop$tailrec as fun loop$tailrec¹(x, y) {
 //│   loop loopLabel:
 //│     let scrut, scrut1, tmp, tmp1, tmp2;
 //│     set scrut = ===⁰(y, 0);
@@ -403,7 +428,7 @@ loop(5)(5)
 //│         match scrut1
 //│           true =>
 //│             set tmp = -⁰(y, 1);
-//│             set tmp1 = loop$tailrec²(5, tmp);
+//│             set tmp1 = loop$tailrec¹(5, tmp);
 //│             return +⁰(1, tmp1)
 //│           else
 //│             set tmp2 = -⁰(x, 1);
@@ -414,8 +439,8 @@ loop(5)(5)
 //│   unreachable /* Rest of abortive labelled block */
 //│ };
 //│ @inline
-//│ define loop⁴ as fun loop⁵(x)(y) { return loop$tailrec²(x, y) };
-//│ return loop$tailrec²(5, 5)
+//│ define loop⁴ as fun loop⁵(x)(y) { return loop$tailrec¹(x, y) };
+//│ return loop$tailrec¹(5, 5)
 //│ —————————————————| Output |—————————————————————————————————————————————————————————————————————————
 //│ = 5
 
@@ -452,7 +477,7 @@ fun f(n)(a)(...z) =
 //│ ——————————————| Optimized IR |——————————————————————————————————————————————————————————————————————
 //│ let f$tailrec;
 //│ @private
-//│ define f$tailrec as fun f$tailrec²(n, a, z) {
+//│ define f$tailrec as fun f$tailrec³(n, a, z) {
 //│   loop loopLabel:
 //│     let scrut, res, tmp, tmp1;
 //│     set scrut = >⁰(n, 0);
@@ -471,7 +496,7 @@ fun f(n)(a)(...z) =
 //│             set tmp2 = -¹(z.length﹖, 0);
 //│             set inlinedVal = z.slice﹖(1, tmp2);
 //│             set tmp1 = +⁰(a, 1);
-//│             set res = f$tailrec²(n, tmp1, inlinedVal);
+//│             set res = f$tailrec³(n, tmp1, inlinedVal);
 //│             do Predef⁰.print⁰("hi!");
 //│             return res
 //│           else
@@ -480,7 +505,8 @@ fun f(n)(a)(...z) =
 //│     end
 //│   unreachable /* Rest of abortive labelled block */
 //│ };
-//│ define f⁸ as fun f⁹(n)(a)(...z) { return f$tailrec²(n, a, z) };
+//│ @inline
+//│ define f⁸ as fun f⁹(n)(a)(...z) { return f$tailrec³(n, a, z) };
 //│ end
 //│ —————————————————| Output |—————————————————————————————————————————————————————————————————————————
 
diff --git a/hkmc2/shared/src/test/mlscript/tailrec/TailRecOpt.mls b/hkmc2/shared/src/test/mlscript/tailrec/TailRecOpt.mls
index 6faa4adefa..7bbb308d2e 100644
--- a/hkmc2/shared/src/test/mlscript/tailrec/TailRecOpt.mls
+++ b/hkmc2/shared/src/test/mlscript/tailrec/TailRecOpt.mls
@@ -57,9 +57,11 @@ f(10000, 20000, 0)
 //│     end
 //│   end
 //│ };
+//│ @inline
 //│ define g⁰ as fun g¹(a, b, c, d) {
 //│   return g_f⁰(0, a, b, c, d)
 //│ };
+//│ @inline
 //│ define f⁰ as fun f¹(a, b, c) {
 //│   return g_f⁰(1, a, b, c, undefined)
 //│ };
@@ -190,9 +192,11 @@ fun g(n) =
 //│     end
 //│   end
 //│ };
+//│ @inline
 //│ define f² as fun f³(n, a, b, c, d, ...e) {
 //│   return f_g⁰(0, n, e)
 //│ };
+//│ @inline
 //│ define g² as fun g³(n) { return f_g⁰(1, n, undefined) };
 //│ end
 //│ —————————————————| Output |—————————————————————————————————————————————————————————————————————————
@@ -209,7 +213,7 @@ fun f(x) =
     @tailcall f(x)
   @tailcall g()
 //│ ╔══[COMPILATION ERROR] This call is not in tail position.
-//│ ║  l.208: 	    @tailcall f(x)
+//│ ║  l.212: 	    @tailcall f(x)
 //│ ╙──       	              ^^^^
 
 :lift
@@ -319,7 +323,9 @@ fun g(x) =
 //│     end
 //│   end
 //│ };
+//│ @inline
 //│ define f⁶ as fun f⁷(x) { return f_g¹(0) };
+//│ @inline
 //│ define g⁴ as fun g⁵(x) { return f_g¹(1) };
 //│ end
 //│ —————————————————| Output |—————————————————————————————————————————————————————————————————————————
@@ -363,10 +369,10 @@ module A with
     @tailcall g(x - 1)
 A.f(10000)
 //│ ╔══[COMPILATION ERROR] This tail call exits the current scope and is not optimized.
-//│ ║  l.362: 	    fun g(x) = if x < 0 then 0 else @tailcall f(x)
+//│ ║  l.368: 	    fun g(x) = if x < 0 then 0 else @tailcall f(x)
 //│ ╙──       	                                              ^^^^
 //│ ╔══[COMPILATION ERROR] This tail call exits the current scope and is not optimized.
-//│ ║  l.363: 	    @tailcall g(x - 1)
+//│ ║  l.369: 	    @tailcall g(x - 1)
 //│ ╙──       	              ^^^^^^^^
 //│ = 0
 
@@ -393,12 +399,12 @@ class A with
   fun g(x) = if x == 0 then 1 else @tailcall f(x - 1)
 (new A).f(10)
 //│ ╔══[COMPILATION ERROR] Calls from class methods cannot yet be marked @tailcall.
-//│ ║  l.392: 	  @tailrec fun f(x) = if x == 0 then 0 else @tailcall g(x - 1)
+//│ ║  l.398: 	  @tailrec fun f(x) = if x == 0 then 0 else @tailcall g(x - 1)
 //│ ╙──       	                                                      ^^^^^^^^
 //│ ╔══[COMPILATION ERROR] Class methods may not yet be marked @tailrec.
-//│ ║  l.392: 	  @tailrec fun f(x) = if x == 0 then 0 else @tailcall g(x - 1)
+//│ ║  l.398: 	  @tailrec fun f(x) = if x == 0 then 0 else @tailcall g(x - 1)
 //│ ╙──       	               ^
 //│ ╔══[COMPILATION ERROR] Calls from class methods cannot yet be marked @tailcall.
-//│ ║  l.393: 	  fun g(x) = if x == 0 then 1 else @tailcall f(x - 1)
+//│ ║  l.399: 	  fun g(x) = if x == 0 then 1 else @tailcall f(x - 1)
 //│ ╙──       	                                             ^^^^^^^^
 //│ = 0

From 4e2ce1784a6c2c5d0969cbccab1ecbdef5d42191 Mon Sep 17 00:00:00 2001
From: CAG2Mark <git@markng.com>
Date: Thu, 27 Aug 2026 21:26:28 +0800
Subject: [PATCH 09/13] update test comment

---
 hkmc2/shared/src/test/mlscript/tailrec/MultiArgLists.mls | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/hkmc2/shared/src/test/mlscript/tailrec/MultiArgLists.mls b/hkmc2/shared/src/test/mlscript/tailrec/MultiArgLists.mls
index 19ffbc2191..e969ad47c1 100644
--- a/hkmc2/shared/src/test/mlscript/tailrec/MultiArgLists.mls
+++ b/hkmc2/shared/src/test/mlscript/tailrec/MultiArgLists.mls
@@ -406,7 +406,7 @@ fun f = loop(1000)(0)
 //│ end
 //│ —————————————————| Output |—————————————————————————————————————————————————————————————————————————
 
-// Ensure the function is inlined
+// Ensure the non-tail call is calls the loop definition and is correctly handled
 :soir
 fun loop(x)(y) =
   if y === 0 then 0
@@ -444,6 +444,7 @@ loop(5)(5)
 //│ —————————————————| Output |—————————————————————————————————————————————————————————————————————————
 //│ = 5
 
+// Ensure the spread args are properly handled
 fun f(n)(a, b, c, d, ...e)(m) =
   if n > 0 then @tailcall g(n)(m + 1)
   else [e, m]

From e79bdee7f2480a90232858b0576ec48c647e6d2b Mon Sep 17 00:00:00 2001
From: CAG2Mark <git@markng.com>
Date: Thu, 27 Aug 2026 23:08:26 +0800
Subject: [PATCH 10/13] address review

---
 .../src/main/scala/hkmc2/codegen/Block.scala  |  2 +-
 .../main/scala/hkmc2/codegen/TailRecOpt.scala | 22 +++++++++----------
 hkmc2/shared/src/test/mlscript/HkScratch.mls  | 21 +++++++++++++++++-
 .../test/mlscript/tailrec/MultiArgLists.mls   |  2 +-
 4 files changed, 32 insertions(+), 15 deletions(-)

diff --git a/hkmc2/shared/src/main/scala/hkmc2/codegen/Block.scala b/hkmc2/shared/src/main/scala/hkmc2/codegen/Block.scala
index bcc34c550e..a1ad82c03d 100644
--- a/hkmc2/shared/src/main/scala/hkmc2/codegen/Block.scala
+++ b/hkmc2/shared/src/main/scala/hkmc2/codegen/Block.scala
@@ -682,7 +682,7 @@ final case class FunDefn(
   lazy val affineInfo: Ls[Int] =
     annotations.collect:
       case Annot.Affine(whichParamList) => whichParamList
-  lazy val paramSyms: Ls[VarSymbol] = params.flatMap(_.paramSyms)
+  lazy val allParamSyms: Ls[VarSymbol] = params.flatMap(_.paramSyms)
 
   // * This deliberately is not a lazy val: its initialization would synchronize on the JVM.
   // * Computing the summary is pure, and a reference write is atomic, so concurrent traversals may
diff --git a/hkmc2/shared/src/main/scala/hkmc2/codegen/TailRecOpt.scala b/hkmc2/shared/src/main/scala/hkmc2/codegen/TailRecOpt.scala
index 2b8e7dfe29..3dc209c1c6 100644
--- a/hkmc2/shared/src/main/scala/hkmc2/codegen/TailRecOpt.scala
+++ b/hkmc2/shared/src/main/scala/hkmc2/codegen/TailRecOpt.scala
@@ -250,9 +250,9 @@ class TailRecOpt(checkAnnotations: Bool)(using State, TL, Raise):
     * @param plist The parameter list to apply.
     * @param args The argument list.
     * @return A tuple `(Block => Block, List[Path])`, where:
-    * - The first parameter contains the code that breaks up the arguments into the shape expected by the parameter list, and
+    * - The first return value contains the code that breaks up the arguments into the shape expected by the parameter list, and
     *   should be applied to the remaining code;
-    * - The second parameter is a list of paths containing the arguments in order. If there is a spread parameter, it will be
+    * - The second return value is a list of paths containing the arguments in order. If there is a spread parameter, it will be
     *   the last one.
     */
   def forceSpread(plist: ParamList, args: List[Arg]): (Block => Block, List[Path]) =
@@ -344,9 +344,9 @@ class TailRecOpt(checkAnnotations: Bool)(using State, TL, Raise):
     val paramSyms =
         if hasWrapper then 
           if funsLen === 1 then
-            funs.head.paramSyms.map(v => VarSymbol(Tree.Ident(v.id.name)))
+            funs.head.allParamSyms.map(v => VarSymbol(Tree.Ident(v.id.name)))
           else for i <- 0 until maxParamLen yield VarSymbol(Tree.Ident("param" + i))
-        else funs.head.paramSyms
+        else funs.head.allParamSyms
       .toList
     val paramSymsArr = ArrayBuffer.from(paramSyms)
     // Function -> param -> param symbol in the rewritten function
@@ -371,10 +371,10 @@ class TailRecOpt(checkAnnotations: Bool)(using State, TL, Raise):
     
     def rewriteKnownCall(callee: FunDefn, flattenedArgs: List[Path]) =
       if !hasWrapper then lastWords("Tried to rewrite a call to a non-existent loop definition.")
-      if callee.paramSyms.length =/= flattenedArgs.length then lastWords("Incorrect function call arity.")
+      if callee.allParamSyms.length =/= flattenedArgs.length then lastWords("Incorrect function call arity.")
       // Fill in the argument list with the arguments in the correct position by applying the paramSym -> arg map to
       // the loop definitions parameter list.
-      val argsMap = (callee.paramSyms.map(paramSymsMap(callee.dSym)) zip flattenedArgs).toMap
+      val argsMap = (callee.allParamSyms.map(paramSymsMap(callee.dSym)) zip flattenedArgs).toMap
       val args = paramSyms.map: s =>
         argsMap.get(s) match
           case Some(pth) => Arg(N, pth)
@@ -383,7 +383,7 @@ class TailRecOpt(checkAnnotations: Bool)(using State, TL, Raise):
       Call(loopDefnPath, argsWithId ne_:: Nil)(CallMetadata.defaultMlsFun)
     
     class FunRewriter(f: FunDefn) extends BlockTransformerShallow(SymbolSubst.Id):
-      val params = f.paramSyms
+      val params = f.allParamSyms
       val paramsSet = f.params.toSet
       val paramsIdxes = params.zipWithIndex.toMap
       
@@ -509,9 +509,6 @@ class TailRecOpt(checkAnnotations: Bool)(using State, TL, Raise):
                         case x => x
                       ret
                   case CallArgsResult.ForceSpread =>
-                    // Forcibly spread the args in an array.
-                    // Assume the lengths are correct
-                    
                     // We can safely remove all of the symbols from this parameter list from `assignedSyms` at this stage,
                     // because the RHS of every parameter will be computed when spreading them in the tuple, which happens
                     // before any of the param symbols are assigned to.
@@ -535,7 +532,8 @@ class TailRecOpt(checkAnnotations: Bool)(using State, TL, Raise):
       // We explicitly rewrite *all* fully applied calls to functions within the SCC. Tail calls are rewritten using a
       // `continue`, while other calls are rewritten as a call to the merged function. This is to make the tailrec
       // optimizer pass idempotent. Without this, the subsequent tailrec optimizer passes could see the merged and wrapper
-      // functions as an SCC and try to rewrite the wrapper's tail call.
+      // functions as an SCC and try to rewrite the wrapper's tail call. Note that selections (and thus calls to
+      // parameter-less module methods) are not yet supported.
       override def applyResult(r: Result)(k: Result => Block): Block = r match
         case c @ Call(Value.MemberRef(bms, calleeSym: TermSymbol), args) if hasWrapper => funsMap.get(calleeSym) match
           case Some(callee) if isExactlySaturatedCall(c, callee) =>
@@ -591,7 +589,7 @@ class TailRecOpt(checkAnnotations: Bool)(using State, TL, Raise):
       (N, defn :: Nil)
     else
       val wrappers = funs.map: f =>
-        val paramArgs = f.paramSyms.map(s => s.asSimpleRef)
+        val paramArgs = f.allParamSyms.map(s => s.asSimpleRef)
         val newBod = Return(
           rewriteKnownCall(f, paramArgs),
         )
diff --git a/hkmc2/shared/src/test/mlscript/HkScratch.mls b/hkmc2/shared/src/test/mlscript/HkScratch.mls
index 48d7326643..b16263b109 100644
--- a/hkmc2/shared/src/test/mlscript/HkScratch.mls
+++ b/hkmc2/shared/src/test/mlscript/HkScratch.mls
@@ -8,4 +8,23 @@
 // :d
 // :todo
 
-
+:sjs
+module M with
+  fun f = g
+  fun g = f
+//│ ————————————| JS (unsanitized) |————————————————————————————————————————————————————————————————————
+//│ let M1;
+//│ (class M {
+//│   static {
+//│     M1 = this
+//│   }
+//│   static get f() {
+//│     return M.g;
+//│   }
+//│   static get g() {
+//│     return M.f;
+//│   }
+//│   toString() { return runtime.render(this); }
+//│   static [definitionMetadata] = ["class", "M"];
+//│ });
+//│ —————————————————| Output |—————————————————————————————————————————————————————————————————————————
diff --git a/hkmc2/shared/src/test/mlscript/tailrec/MultiArgLists.mls b/hkmc2/shared/src/test/mlscript/tailrec/MultiArgLists.mls
index e969ad47c1..46040e9699 100644
--- a/hkmc2/shared/src/test/mlscript/tailrec/MultiArgLists.mls
+++ b/hkmc2/shared/src/test/mlscript/tailrec/MultiArgLists.mls
@@ -406,7 +406,7 @@ fun f = loop(1000)(0)
 //│ end
 //│ —————————————————| Output |—————————————————————————————————————————————————————————————————————————
 
-// Ensure the non-tail call is calls the loop definition and is correctly handled
+// Ensure the non-tail call is rewritten to call the loop definition and is correctly handled
 :soir
 fun loop(x)(y) =
   if y === 0 then 0

From fedba3f34c6349b0b96dc3f1b6f604a82f6d9371 Mon Sep 17 00:00:00 2001
From: CAG2Mark <git@markng.com>
Date: Thu, 27 Aug 2026 23:12:06 +0800
Subject: [PATCH 11/13] address comment

---
 .../main/scala/hkmc2/codegen/TailRecOpt.scala |  2 +-
 .../src/test/mlscript/tailrec/TailRecOpt.mls  | 62 +++++++++++++++----
 2 files changed, 50 insertions(+), 14 deletions(-)

diff --git a/hkmc2/shared/src/main/scala/hkmc2/codegen/TailRecOpt.scala b/hkmc2/shared/src/main/scala/hkmc2/codegen/TailRecOpt.scala
index 3dc209c1c6..4f33807906 100644
--- a/hkmc2/shared/src/main/scala/hkmc2/codegen/TailRecOpt.scala
+++ b/hkmc2/shared/src/main/scala/hkmc2/codegen/TailRecOpt.scala
@@ -535,7 +535,7 @@ class TailRecOpt(checkAnnotations: Bool)(using State, TL, Raise):
       // functions as an SCC and try to rewrite the wrapper's tail call. Note that selections (and thus calls to
       // parameter-less module methods) are not yet supported.
       override def applyResult(r: Result)(k: Result => Block): Block = r match
-        case c @ Call(Value.MemberRef(bms, calleeSym: TermSymbol), args) if hasWrapper => funsMap.get(calleeSym) match
+        case c @ CallToFun(calleeSym) if hasWrapper => funsMap.get(calleeSym) match
           case Some(callee) if isExactlySaturatedCall(c, callee) =>
             val calleeParamsMap = paramSymsMap(callee.dSym)
             val argListResults = callee.params.zip(c.argss).map:
diff --git a/hkmc2/shared/src/test/mlscript/tailrec/TailRecOpt.mls b/hkmc2/shared/src/test/mlscript/tailrec/TailRecOpt.mls
index 7bbb308d2e..5dd1d4b581 100644
--- a/hkmc2/shared/src/test/mlscript/tailrec/TailRecOpt.mls
+++ b/hkmc2/shared/src/test/mlscript/tailrec/TailRecOpt.mls
@@ -301,22 +301,23 @@ a.x
 
 // Make sure the tailrec pass is idempotent by ensuring non-tail calls to functions in the SCC are rewritten as calls to the loop definition.
 :soir
-:noInline
 fun f(x) = g(x)
 fun g(x) =
   f(x)
+  print(x)
   0
 //│ ——————————————| Optimized IR |——————————————————————————————————————————————————————————————————————
 //│ let f_g;
 //│ @private
-//│ define f_g as fun f_g¹(id) {
+//│ define f_g as fun f_g¹(id, param0) {
 //│   loop loopLabel:
 //│     match id
 //│       0 =>
 //│         set id = 1;
 //│         continue loopLabel
 //│       1 =>
-//│         do f_g¹(0);
+//│         do f_g¹(0, param0);
+//│         do Predef⁰.print⁰(param0);
 //│         return 0
 //│       else
 //│         end
@@ -324,9 +325,44 @@ fun g(x) =
 //│   end
 //│ };
 //│ @inline
-//│ define f⁶ as fun f⁷(x) { return f_g¹(0) };
+//│ define f⁶ as fun f⁷(x) {
+//│   return f_g¹(0, x)
+//│ };
 //│ @inline
-//│ define g⁴ as fun g⁵(x) { return f_g¹(1) };
+//│ define g⁴ as fun g⁵(x) { return f_g¹(1, x) };
+//│ end
+//│ —————————————————| Output |—————————————————————————————————————————————————————————————————————————
+
+:soir
+module M with
+  fun f(x) = g(x)
+  fun g(x) =
+    f(x)
+    print(x)
+    0
+//│ ——————————————| Optimized IR |——————————————————————————————————————————————————————————————————————
+//│ define M⁰ as class M¹
+//│ module M² {
+//│   method f_g² = fun f_g³(id, param0) {
+//│     loop loopLabel:
+//│       match id
+//│         0 =>
+//│           set id = 1;
+//│           continue loopLabel
+//│         1 =>
+//│           do M².this.f_g³(0, param0);
+//│           do Predef⁰.print⁰(param0);
+//│           return 0
+//│         else
+//│           end
+//│       end
+//│     end
+//│   }
+//│   method f⁸ = fun f⁹(x) {
+//│     return M².this.f_g³(0, x)
+//│   }
+//│   method g⁶ = fun g⁷(x) { return M².this.f_g³(1, x) }
+//│ };
 //│ end
 //│ —————————————————| Output |—————————————————————————————————————————————————————————————————————————
 
@@ -339,7 +375,7 @@ fun f(n, x, ...y) =
     f(0, ...[1, 2, 3])
     f(0, 1, 2, 3)
 //│ ——————————————| Optimized IR |——————————————————————————————————————————————————————————————————————
-//│ define f⁸ as fun f⁹(n, x, ...y) {
+//│ define f¹⁰ as fun f¹¹(n, x, ...y) {
 //│   loop loopLabel:
 //│     let scrut, tmp;
 //│     set scrut = ===⁰(n, 0);
@@ -347,9 +383,9 @@ fun f(n, x, ...y) =
 //│       true =>
 //│         return [x, y]
 //│       else
-//│         do f⁹(0, 1, 2, 3);
+//│         do f¹¹(0, 1, 2, 3);
 //│         set tmp = [1, 2, 3];
-//│         do f⁹(0, ...tmp);
+//│         do f¹¹(0, ...tmp);
 //│         set n = 0;
 //│         set x = 1;
 //│         set y = mut [2, 3];
@@ -369,10 +405,10 @@ module A with
     @tailcall g(x - 1)
 A.f(10000)
 //│ ╔══[COMPILATION ERROR] This tail call exits the current scope and is not optimized.
-//│ ║  l.368: 	    fun g(x) = if x < 0 then 0 else @tailcall f(x)
+//│ ║  l.404: 	    fun g(x) = if x < 0 then 0 else @tailcall f(x)
 //│ ╙──       	                                              ^^^^
 //│ ╔══[COMPILATION ERROR] This tail call exits the current scope and is not optimized.
-//│ ║  l.369: 	    @tailcall g(x - 1)
+//│ ║  l.405: 	    @tailcall g(x - 1)
 //│ ╙──       	              ^^^^^^^^
 //│ = 0
 
@@ -399,12 +435,12 @@ class A with
   fun g(x) = if x == 0 then 1 else @tailcall f(x - 1)
 (new A).f(10)
 //│ ╔══[COMPILATION ERROR] Calls from class methods cannot yet be marked @tailcall.
-//│ ║  l.398: 	  @tailrec fun f(x) = if x == 0 then 0 else @tailcall g(x - 1)
+//│ ║  l.434: 	  @tailrec fun f(x) = if x == 0 then 0 else @tailcall g(x - 1)
 //│ ╙──       	                                                      ^^^^^^^^
 //│ ╔══[COMPILATION ERROR] Class methods may not yet be marked @tailrec.
-//│ ║  l.398: 	  @tailrec fun f(x) = if x == 0 then 0 else @tailcall g(x - 1)
+//│ ║  l.434: 	  @tailrec fun f(x) = if x == 0 then 0 else @tailcall g(x - 1)
 //│ ╙──       	               ^
 //│ ╔══[COMPILATION ERROR] Calls from class methods cannot yet be marked @tailcall.
-//│ ║  l.399: 	  fun g(x) = if x == 0 then 1 else @tailcall f(x - 1)
+//│ ║  l.435: 	  fun g(x) = if x == 0 then 1 else @tailcall f(x - 1)
 //│ ╙──       	                                             ^^^^^^^^
 //│ = 0

From a8087fd04111e03af9d77528672a2ac101102a17 Mon Sep 17 00:00:00 2001
From: CAG2Mark <git@markng.com>
Date: Thu, 27 Aug 2026 23:13:00 +0800
Subject: [PATCH 12/13] revert hkscratch

---
 hkmc2/shared/src/test/mlscript/HkScratch.mls | 22 ++------------------
 1 file changed, 2 insertions(+), 20 deletions(-)

diff --git a/hkmc2/shared/src/test/mlscript/HkScratch.mls b/hkmc2/shared/src/test/mlscript/HkScratch.mls
index b16263b109..ef38e8b363 100644
--- a/hkmc2/shared/src/test/mlscript/HkScratch.mls
+++ b/hkmc2/shared/src/test/mlscript/HkScratch.mls
@@ -8,23 +8,5 @@
 // :d
 // :todo
 
-:sjs
-module M with
-  fun f = g
-  fun g = f
-//│ ————————————| JS (unsanitized) |————————————————————————————————————————————————————————————————————
-//│ let M1;
-//│ (class M {
-//│   static {
-//│     M1 = this
-//│   }
-//│   static get f() {
-//│     return M.g;
-//│   }
-//│   static get g() {
-//│     return M.f;
-//│   }
-//│   toString() { return runtime.render(this); }
-//│   static [definitionMetadata] = ["class", "M"];
-//│ });
-//│ —————————————————| Output |—————————————————————————————————————————————————————————————————————————
+
+

From 22729210ccfc024a251434c29687da4f3f78bfcb Mon Sep 17 00:00:00 2001
From: CAG2Mark <git@markng.com>
Date: Thu, 27 Aug 2026 23:13:38 +0800
Subject: [PATCH 13/13] revert hkscratch

---
 hkmc2/shared/src/test/mlscript/HkScratch.mls | 1 -
 1 file changed, 1 deletion(-)

diff --git a/hkmc2/shared/src/test/mlscript/HkScratch.mls b/hkmc2/shared/src/test/mlscript/HkScratch.mls
index ef38e8b363..48d7326643 100644
--- a/hkmc2/shared/src/test/mlscript/HkScratch.mls
+++ b/hkmc2/shared/src/test/mlscript/HkScratch.mls
@@ -9,4 +9,3 @@
 // :todo
 
 
-