Unfortunately, Perl's syntactic texture is more than just a list of words. To make meaningful code changes, you need to work on the parse tree.

You could take a look at HP's RPL ("Reverse Polish Lisp"), which does things this way (it mimics Forth, where subs are (almost) nothing more than lists of words. Available on any of their programmable calculators, at least since the HP-41 (I think), and including the HP-48 and HP-49 series.