/** * @param mixed $collection * @param string $column * @return mixed[] */ function collection_column($collection, $column) { assert('is_iterable($collection)'); return collection_map($collection, function ($v) use($column) { return map_get($v, $column); }); }
/** * @param array|Iterator $collection * @return Iterator */ function squaresOf($collection) { return collection_map($collection, function ($number) { return $number ** 2; }); }