Named values in tuples with Typebox

[marijn]

First things first: Thanks for Typebox, you have made something useful and interoperable 🫶

Named tuple values are available in typescript native tuple syntax

export type Lat = `${number}°N`;
export type Long = `${string}°E`;
export type GeoCoordinate = [
    lat: Lat,
    long: Long
];

As far as I can tell this is not available with Typebox, but asking never hurts.
For now this type is one that I've retained hard-coded over deriving it from the schema, because I find it helps with he developer experience of the people that have to interact with my tuple.

[sinclairzx81]

@marijn Hi! thanks :)

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As far as I can tell this is not available with Typebox, but asking never hurts. For now this type is one that I've retained hard-coded over deriving it from the schema, because I find it helps with he developer experience of the people that have to interact with my tuple.

Yeah, I'd really like to support this. Unfortunately, it doesn't appear TypeScript supports programmatic element labeling (yet) ... but it might be possible in future. To support, would need TypeScript to allow the following (where the Name argument is observed in the label position)

TypeScript Reference

// Make Labelled Element
type Label<Name extends string, Value extends number, Result extends [number] = [Name: Value]> = Result
//         ^                                                                     ^
//         Unused Argument                                         Label (Not Generic Argument)

// Assign Labels to Values
type Labels<Values extends number[], Result extends unknown[] = []> = (
  Values extends [infer L extends number, ...infer R extends number[]]
    ? Labels<R, [...Result, ...Label<`Foo${Result['length']}`, L>]>
    : Result
)

// Example
type A = [1, 2, 3]

type B = Labels<A>  // actual: [Name: 1, Name: 2, Name: 3]
                    // expect: [Foo0: 1, Foo1: 2, Foo3: 3]

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TypeBox has made some provisions for this feature, and element labeling is technically supported with Script (...) today, but sadly needs to infer without labels for now, so just waiting on TypeScript to provide language support to go further.

TypeScript Reference

import Type from 'typebox'

// Tip: Use TS7 for Unicode ° inference 
export type GeoCoordinate = Type.Static<typeof GeoCoordinate> // [`${number}°N`, `${string}°E`]
export type Lat = Type.Static<typeof Lat>                     // `${number}°N`
export type Long = Type.Static<typeof Long>                   // `${string}°E`

const { Lat, Long, GeoCoordinate } = Type.Script(`
  export type Lat = \`\${number}°N\`;
  export type Long = \`\${string}°E\`;
  export type GeoCoordinate = [
    lat: Lat,
    long: Long
  ];
`)

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Hope this brings some insight!
All the best!
S