That looks good, although one may wonder at the long term support prospects (the author says "I'm in the process of transitioning away from PHP to Ruby.").

For your delectation, other PHP repls include :

- The basic built-in repl "php -a"

- Facebooks phpsh : http://phpsh.org/

- PHP Shell : http://jan.kneschke.de/projects/php-shell

- php-repl : https://github.com/tailrecursion/wigwam

If you want something more customised to your needs, investigate the plethora of readln and posix functions in PHP and dive right in!