Add unzipWith

snippets/unzipWith.md

@@ -0,0 +1,23 @@
+### unzipWith
+
+Creates an array of elements, ungrouping the elements in an array produced by [zip](#zip) and applying the provided function.
+
+Use `Math.max.apply()` to get the longest subarray in the array, `Array.map()` to make each element an array.
+Use `Array.reduce()` and `Array.forEach()` to map grouped values to individual arrays.
+Use `Array.map()` and the spread operator (`...`) to apply `fn` to each individual group of elements.
+
+```js
+const unzipWith = (arr, fn) =>
+  arr
+    .reduce(
+      (acc, val) => (val.forEach((v, i) => acc[i].push(v)), acc),
+      Array.from({
+        length: Math.max(...arr.map(x => x.length)),
+      }).map(x => [])
+    )
+    .map(val => fn(...val));
+```
+
+```js
+unzipWith([[1, 10, 100], [2, 20, 200]], (...args) => args.reduce((acc, v) => acc + v, 0)); // [3, 30, 300]
+```