3v4l.org

run code in 300+ PHP versions simultaneously
<?php $path = null; $list = array('f1.txt', 'f2.txt', 'f3.txt', 'f4.txt'); $mapping = array_map(function($item) use ($path) { return $path ? $path . $item : $item; }, $list); var_dump($mapping);

preferences:
49.35 ms | 402 KiB | 5 Q