# Pastebin a6T061fj
(defun cartesian (l) 
  (cond ((null l) nil) 
        ((null (cdr l)) 
         (mapcar #'list (car l))) 
        (t (mapcan #'(lambda (x) (mapcar #'(lambda (y) (cons y x)) (car l))) 
                   (cartesian (cdr l))))))