Add bifurcate, bifurcateBy

snippets/bifurcate.md

@@ -0,0 +1,17 @@
+### bifurcate
+
+Splits values into two groups. If an element in `filter` is truthy, the corresponding element in the collection belongs to the first group; otherwise, it belongs to the second group.
+
+Use `Array.reduce()` and `Array.push()` to add elements to groups, based on `filter`.
+
+```js
+const bifurcate = (arr, filter) =>
+  arr.reduce((acc, val, i) => (acc[filter[i] ? 0 : 1].push(val), acc), [
+    [],
+    [],
+  ]);
+```
+
+```js
+bifurcate([ 'beep', 'boop', 'foo', 'bar' ], [ true, true, false, true ]); // [ ['beep', 'boop', 'bar'], ['foo'] ]
+```

snippets/bifurcateBy.md

@@ -0,0 +1,17 @@
+### bifurcateBy
+
+Splits values into two groups according to a predicate function, which specifies which group an element in the input collection belongs to. If the predicate function returns a truthy value, the collection element belongs to the first group; otherwise, it belongs to the second group.
+
+Use `Array.reduce()` and `Array.push()` to add elements to groups, based on the value returned by `fn` for each element.
+
+```js
+const bifurcateBy = (arr, fn) =>
+  arr.reduce((acc, val, i) => (acc[fn(val, i) ? 0 : 1].push(val), acc), [
+    [],
+    [],
+  ]);
+```
+
+```js
+bifurcateBy([ 'beep', 'boop', 'foo', 'bar' ], x => x[0] === 'b'); // [ ['beep', 'boop', 'bar'], ['foo'] ]
+```