Well, if by "one" you mean you, or me, or a very small handful of other people, sure. We can do the same with XS, too--it's still far less safe than Lisp macros, and a bare step above pack "p" and slamming bits directly into memory. It is, however, acting on the final internal representation of the program, rather than on the parsed version of the program. (Though in perl's case there is no actual difference, as there's no 'just parsed' version to manipulate before it gets turned into the structures that get executed)