Returns List<List<A>>

The list having permutations.

Examples

import { empty, fromArray, permutations, range, toArray } from "./list.ts";
import { assertEquals } from "../deps.ts";

assertEquals(permutations(empty()), empty());

const subSeq = permutations(range(1, 5));
const sequences = toArray(subSeq).map((seq) => toArray(seq));
assertEquals(sequences, [
    [1, 2, 3, 4],
    [2, 1, 3, 4],
    [3, 2, 1, 4],
    [2, 3, 1, 4],
    [3, 1, 2, 4],
    [1, 3, 2, 4],
    [4, 3, 2, 1],
    [3, 4, 2, 1],
    [3, 2, 4, 1],
    [4, 2, 3, 1],
    [2, 4, 3, 1],
    [2, 3, 4, 1],
    [4, 1, 2, 3],
    [1, 4, 2, 3],
    [1, 2, 4, 3],
    [4, 2, 1, 3],
    [2, 4, 1, 3],
    [2, 1, 4, 3],
    [4, 1, 3, 2],
    [1, 4, 3, 2],
    [1, 3, 4, 2],
    [4, 3, 1, 2],
    [3, 4, 1, 2],
    [3, 1, 4, 2],
]);
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