froebel/unzip.js

TypeScript utility library

"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.unzipWith = exports.default = void 0;

/**
 * Reverse of {@link zip}. Takes a list of tuples and deconstructs them into
 * an array (of length of the tuples length) of lists each containing all the
 * elements in all tuples at the lists index.
 *
 * @example
 * const [nums, chars] = unzip([1,'a'], [2,'b'], [3,'c'])
 * console.log(nums)  // prints: [1, 2, 3]
 * console.log(chars) // prints: ['a','b','c']
 */
const unzip = (...zipped) => zipped.reduce((a, c) => c.map((v, i) => [...(a[i] ?? []), v]), []);

var _default = unzip;
/**
 * Same as {@link unzip} but accepts an `unzipper` function for each tuple
 * index. The `unzipper`'s return value is used as the value in the list at
 * that index returned from `unzipWith`.
 *
 * The `unzipper` takes the current element as its first argument, an
 * accumulator as second argument (initially `undefined`) and its return value
 * is the accumulator passed into the next invocation.
 *
 * @example
 * const [nums, str] = unzipWith(
 *   [ [1,'a'], [2,'b'], [3,'c'] ],
 *   (n, acc: number[] = []) => [...acc, n],
 *   (c, str = '') => str + c
 * )
 *
 * console.log(nums) // prints: [1, 2, 3]
 * console.log(str)  // prints: 'abc'
 */

exports.default = _default;

const unzipWith = (zipped, ...unzippers) => zipped.reduce((a, c) => c.map((v, i) => unzippers[i](v, a[i])), []);

exports.unzipWith = unzipWith;
module.exports = Object.assign(exports.default || {}, exports);