zipWith.ts

// Copyright (c) 2020 Jozty. All rights reserved. MIT license.

import type { PH } from './utils/types.ts';
import curryN from './utils/curry_n.ts';

// @types
type ZipWith_1<T1, T2> = <R>(fn: (a: T1, b: T2) => R) => R[];

type ZipWith_2<T1, R> = (list1: T1[]) => R[];

type ZipWith_3<T2, R> = (list2: T2[]) => R[];

type ZipWith_2_3<T1, T2, R> =
  & ((list1: T1[]) => ZipWith_3<T2, R>)
  & ((
    list1: PH,
    list2: T2[],
  ) => ZipWith_2<T1, R>)
  & ((list1: T1[], list2: T2[]) => R[]);

type ZipWith_1_3<T1> =
  & (<T2, R>(fn: (a: T1, b: T2) => R) => ZipWith_3<T2, R>)
  & (<T2>(fn: PH, list2: T2[]) => ZipWith_1<T1, T2>)
  & (<T2, R>(fn: (a: T1, b: T2) => R, list2: T2[]) => R[]);

type ZipWith_1_2<T2> =
  & (<T1, R>(fn: (a: T1, b: T2) => R) => ZipWith_2<T1, R>)
  & (<T1>(fn: PH, list1: T1[]) => ZipWith_1<T1, T2>)
  & (<T1, R>(fn: (a: T1, b: T2) => R, list1: T1[]) => R[]);

type ZipWith =
  & (<T1, T2, R>(fn: (a: T1, b: T2) => R) => ZipWith_2_3<T1, T2, R>)
  & (<T1>(fn: PH, list1: T1[]) => ZipWith_1_3<T1>)
  & (<T2>(fn: PH, list1: PH, list2: T2[]) => ZipWith_1_2<T2>)
  & (<T1, T2, R>(fn: (a: T1, b: T2) => R, list1: T1[]) => ZipWith_3<T2, R>)
  & (<T1, T2, R>(
    fn: (a: T1, b: T2) => R,
    list1: PH,
    list2: T2[],
  ) => ZipWith_2<T1, R>)
  & (<T1, T2>(fn: PH, list1: T1[], list2: T2[]) => ZipWith_1<T1, T2>)
  & (<T1, T2, R>(fn: (a: T1, b: T2) => R, list1: T1[], list2: T2[]) => R[]);

function _zipWith<T1, T2, R>(
  fn: (a: T1, b: T2) => R,
  list1: T1[],
  list2: T2[],
) {
  const len = Math.min(list1.length, list2.length);
  const result = new Array<R>(len);
  for (let i = 0; i < len; i++) {
    result[i] = fn(list1[i], list2[i]);
  }
  return result;
}

/**
 * Creates a new list out of two passed lists `list1`, `list2`.
 * Each item of new list is calculated by applying equally-positioned pair
 * in both the lists.
 * The returned is truncated to the length of the shorter of the two input lists.
 *
 *      Fae.zipWith(Fae.add, [100, 200, 300], [1, 2, 3]) // [101, 202, 303]
 */
export const zipWith = curryN(3, _zipWith) as ZipWith;