They're written in Perl. Take a look at the sources:<p>tmp: <a href="http://conway.rutgers.edu/~ccshan/wiki/blog/posts/Higher-order_shell/tmp" rel="nofollow">http://conway.rutgers.edu/~ccshan/wiki/blog/posts/Higher-ord...</a><p>keep: 
<a href="http://conway.rutgers.edu/~ccshan/wiki/blog/posts/Higher-order_shell/keep" rel="nofollow">http://conway.rutgers.edu/~ccshan/wiki/blog/posts/Higher-ord...</a>