<?php

function zip() {
    $params = func_get_args();
    $result = call_user_func_array('array_map', array_merge(array(null), $params));
    $length = min(array_map('count', $params));
    return array_slice($result, 0, $length);
};

$a = array(1,2,3,4,5);
$b = array('a','b');

var_dump(zip($a));