;;; with default optimizations
(defun factorial (n)
  (cond ((= n 0) 1)
    (t (* n (factorial (- n 1))))))

;;;-----------------------
;;; usage:
;;;
;;; $ clisp, ecl or cmucl
;;; (load "fact.lisp")
;;; (test1)
;;; or
;;; (test2)

;;; poor, c conversion, :)
#+:clisp
(defun test1 ()
  (format t "~S~&" (factorial 6000)))

#+:clisp
(defun test2 ()
  (compile 'factorial)
  (format t "~S~&" (factorial 40000)))

;;;------------------------
;;; better, :)
#+:ecl
(defun test1 ()
  (format t "~S~&" (factorial 12000)))

#+:ecl
(defun test2 ()
  (compile 'factorial)
  (format t "~S~&" (factorial 80000)))

;;;--------------------------
;;; this is already optimized by default
#+:cmu
(defun test1 ()
  (format t "~S~&" (factorial 100000)))

#+:cmu
(defun test2 ()
  (compile 'factorial)
  (format t "~S~&" (factorial 200000)))

;;; Note:
;;;
;;; - the numbers are random, that means i didn't try to find a limit,
;;; just stop before 'stack overflow' for clisp and ecl, first hit
;;; from cmucl
;;; - no declaration to optimze the compiled code in a specific way