Make PHP's `array_map()` behave more like JavaScript.

map.php

<?php

/**
 * Make PHP `array_map()` more like JavaScript.
 *
 * - Reverse paramaters so array comes first, callback second.
 * - Include index as second argument to callback.
 *
 * @param  array     $arr
 * @param  function  $callback
 * @return array
 */
function map(array $arr, $callback) {
	return array_map($callback, $arr, range(0, count($arr) - 1));
}

// Example
map(['hello', 'goodbye', 'goodnight'], function ($msg, $i) {
	echo "$i - $msg\n";
});