I have no words – I am simply amazed with what Lisp allowed me to do (it deserves a blog post on its own). This kind of functionality (complex, nested loop unrolling) is something that is either implemented in your language’s compiler, or forces you to manually mess up your code (or code generate). Lisp allowed me to do this at compile-time, maintaining at the same time the original (slower) code structure. Mind=blown.