flatMap

Flatten nested set, based on map function.

Alternatives: flat, flatMap.

function flatMap(x, fm, ft)
// x:  a nested set
// fm: map function (v, v, x)
// ft: flatten test function (v, v, x) [is]

const set = require('extra-set');

var x = new Set([
  new Set([1, 2]),
  new Set([3, new Set([4, new Set([5])])])
]);
set.flatMap(x);
// → Set(4) { 1, 2, 3, Set(2) { 4, Set(1) { 5 } } }

set.flatMap(x, v => set.flat(v, 1));
// → Set(5) { 1, 2, 3, 4, Set(1) { 5 } }

set.flatMap(x, v => set.flat(v));
// → Set(5) { 1, 2, 3, 4, 5 }

References

• Array.prototype.flat: MDN web docs
• _.flatten: lodash
• _.flattenDeep: lodash
• _.flattenDepth: lodash
• Array.flatten: sugarjs