マジなマージ

msort.cl

(defun take (n list)
  (if (= n 0) nil (cons (car list) (take (- n 1) (cdr list)))))
 
(defun slice (n list)
  (if (null list) nil (cons (take n list) (slice n (nthcdr n list)))))
 
(defun msort(list pred)
  (cond ((not (consp (car list)))
         (msort (slice 1 list) pred))
        ((equal (cdr list) NIL)
         (car list))
        (t
          (msort (mapcar (lambda (l) (merge 'list (car l) (cadr l) pred))
                         (slice 2 list))
                 pred))))