If you can write something as a function, that's always a better option than making it a macro. It's clear to any clojure programmer what your entropy function does, just like it's clear to any Perl programmer what all that "line noise" is. (Arguably, there isn't much line noise in Perl, only in regular expressions, which every other language has stolen Perl's implementation of. If you want real line noise regexps, try Emacs Lisp without "rx".)
