Variations on a Scheme

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

I'll start with a mostly kawaii (cute) one:

(defun sepples (mosiacpointeroverflow)
  (reduce #'* (loop for grunner from 1 to mosiacpointeroverflow collect grunner) :initial-value 1))


COBRA> (enable-%-syntax)
T
COBRA> #% lambda('(x), expt(2, x)).mapcar(function('oddp).remove-if(list(1,2,3,4,5,6))) %
(4 16 64)
COBRA> (reduce #'* #% lambda('(x), expt(2, x)).mapcar(function('oddp).remove-if(list(1,2,3,4,5,6))) %)
4096

WHERE IS YOUR GOD NOW