froebel/zip.mjs

TypeScript utility library

/**
 * Takes multiple lists and returns a list of tuples containing the value in
 * each list at the current index. If the lists are of different lengths, the
 * returned list of tuples has the length of the shortest passed in list.
 *
 * @example
 * ```
 * const pairs = zip([1,2,3], ['a','b','c'])
 * console.log(pairs) // prints: [[1,'a'], [2,'b'], [3,'c']]
 * ```
 */
const zip = (...lists) => [...Array(Math.min(...lists.map(({
  length
}) => length)))].map((_, i) => lists.map(l => l[i]));

export default zip;
/**
 * Same as {@link zip} but also takes a `zipper` function, that is called for
 * each index with the element at current index in each list as arguments. The
 * result of `zipper` is the element at current index in the list returned from
 * `zipWith`.
 *
 * @example
 * ```
 * const sums = zipWith((a,b) => a+b, [1,2,3], [4,5,6])
 * console.log(sums) // prints: [5,7,9]
 * ```
 */

export const zipWith = (zipper, ...lists) => [...Array(Math.min(...lists.map(({
  length
}) => length)))].map((_, i) => zipper(...lists.map(l => l[i])));