PHP REPL script.

repl.php

#!/usr/bin/env php
<?php
$stdin = fopen('php://stdin', 'r');
$data = '';
while(true) {
        print '> ';
        $data .= fgets($stdin);
        if (preg_match('/\\\\$/', $data)==1) {
                $data = trim($data, "\x00..\x1F \x5C");
        } else {
                eval($data);
                $data = '';
        }
}

I forked this and added code highlighting to your script.