crawling factorial function with no variables

(define (f)
  (begin
    (while (> (length f) 2) (pop f -1))
    (push
      '(if (> 0 1)
         (begin
           (setf ((last f) -1) (* $it ((last f) 1 1))) ;; Increase return value
           (dec ((last f) 1 1)) ;; Change exit condition
           (if (> (length f) 4) ;; Shorten the function if it's too long
             (pop f 2))
           (push (last f) f -1))
         1)
      f -1)
    (setq ((last f) 1 1) (args 0))))