6.001 Section #7                                1 October 1997
Albert R.Meyer


                  LET, LET*, and LETREC scoping Example


(define a 0)
(define b 1)

(let ((a (lambda (n) (+ n (if (procedure? b) 2 (+ a 3)))))
      (b (lambda (n) (* n (if (procedure? a) 4 (+ b 5))))))
  (list (a 6) (b 7)))


(let* ((a (lambda (n) (+ n (if (procedure? b) 2 (+ a 3)))))
       (b (lambda (n) (* n (if (procedure? a) 4 (+ b 5))))))
  (list (a 6) (b 7)))



(letrec ((a (lambda (n) (+ n (if (procedure? b) 2 (+ a 3)))))
         (b (lambda (n) (* n (if (procedure? a) 4 (+ b 5))))))
  (list (a 6) (b 7)))