#lang racket
(require racket/trace)
   
;;; Accumulating values
(define facT-values
  (lambda (n accu)
    (if (= n 1)
	accu
	(facT-values (- n 1) (* n accu)))))

(trace facT-values)


;;; Accumulating values through the detour of applications
(define facT-apps
  (lambda (n accu)
    (if (= n 1)
        ((lambda () accu))
	(facT-apps (- n 1) ((lambda (x) (* n x)) accu)))))
(trace facT-apps)






;;; Accumulating lambda-exps
(define facT-Lambda
  (lambda (n accu)
    (if (= n 1)
	(accu 1)
	(facT-Lambda (- n 1) (lambda (x) (accu (* n x)))))))

(trace facT-Lambda)


;;; Sanitized version
(define fac-cps
  (lambda (n k)
    (if (= n 1)
	(k 1)
	(fac-cps (- n 1) (lambda (x) (k (* n x)))))))