feat(zip): add zip function

Author: djcsdy

index.test.ts

@@ -49,7 +49,8 @@ import {
     split,
     sum,
     tail,
-    takeWhile
+    takeWhile,
+    zip
 } from "./index";
 
 test("isArray", t => {
@@ -413,6 +414,14 @@ test("partitionWhile", t => {
     ]);
 });
 
+test("zip", t => {
+    t.deepEqual(zip([1, 2, 3], [6, 5, 4, 3, 2, 1]), [
+        [1, 6],
+        [2, 5],
+        [3, 4]
+    ]);
+});
+
 test("keyBy", t => {
     const map = keyBy([1, 3, 4, 2, 5, 6], e => (e % 2 === 0 ? "even" : "odd"));
     t.deepEqual(map.get("even"), [4, 2, 6]);

index.ts

@@ -785,6 +785,29 @@ export function partitionWhileFn<T>(
     return array => partitionWhile(array, predicate);
 }
 
+/** Takes two arrays and returns an array of corresponding pairs.
+ *
+ * If one of the supplied arrays is shorter than the other, then the excess
+ * elements of the longer array will be discarded. */
+export function zip<T, U>(a: readonly T[], b: readonly U[]): Array<[T, U]> {
+    const result: Array<[T, U]> = [];
+    for (let i = 0; i < a.length && i < b.length; ++i) {
+        result.push([a[i], b[i]]);
+    }
+    return result;
+}
+
+/** Returns a function that combines the elements of `a` with the elements of
+ * `b` and returns an array of corresponding pairs.
+ *
+ * If one of the supplied arrays is shorter than the other, then the excess
+ * elements of the longer array will be discarded.
+ *
+ * This is the curried variant of {@link zip}. */
+export function zipFn<T, U>(b: readonly U[]): (a: readonly T[]) => Array<[T, U]> {
+    return a => zip(a, b);
+}
+
 export function keyBy<TKey, TElement>(
     array: ArrayLike<TElement>,
     f: (element: TElement, index: number) => TKey