Inject an array with another array a certainposition

Inject_Arrays.php

<?php
/**
 * @param array $needle
 * @param array $haystack
 * @param $position
 * @return array
 */
function inject_this_array($needle=array(),$haystack=array(),$position){
    $new_holder1 =	array_slice($haystack, 0, $position, true);
    $new_holder2 =  array_slice($haystack, $position, count($haystack)-1,true);

    array_push($new_holder1, $needle);
    return $new_holder1 +  $new_holder2;
}