Variations on a Theme

Come up with variations of your favorite toy problems.  The more obfuscated the better.

I'll start with a simple one:

def factorial(n): return reduce(lambda x,y: x*y, range(1,n
+1)) if n > 1 else 1

Clojure is a lisp-1, so there's no need to star-quote functions. It looks more like the python slice operator. How it found its way into lisp I don't know.