#lang racket

;; ---------------------------------------------------------------------
;; This let expression returns a function that refers to itself --
;; without using letrec.
;; ---------------------------------------------------------------------

(define factorial
  (let ((fact #f))
    (set! fact (lambda (n)
                 (if (zero? n)
                     1
                     (* n (fact (sub1 n))))))
    fact))

;; ---------------------------------------------------------------------
;; This is the *translational semantics* for letrec.
;; It really is a syntactic abstraction!
;; ---------------------------------------------------------------------