subsets

List all possible subsets.

Similar: randomSubset, subsets, hasSubset.

function subsets(x, n)
// x: ientries
// n: number of ientries in each subset [-1 ⇒ any]

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

var x = [["a", 1], ["b", 2]];
[...ientries.subsets(x)].map(a => [...a]);
// → [ [], [ [ "a", 1 ] ], [ [ "b", 2 ] ], [ [ "a", 1 ], [ "b", 2 ] ] ]

var x = [["a", 1], ["b", 2], ["c", 3]];
[...ientries.subsets(x)].map(a => [...a]);
// → [
// →   [],
// →   [ [ "a", 1 ] ],
// →   [ [ "b", 2 ] ],
// →   [ [ "a", 1 ], [ "b", 2 ] ],
// →   [ [ "c", 3 ] ],
// →   [ [ "a", 1 ], [ "c", 3 ] ],
// →   [ [ "b", 2 ], [ "c", 3 ] ],
// →   [ [ "a", 1 ], [ "b", 2 ], [ "c", 3 ] ]
// → ]

References

• Data.List.subsequences: Haskell