;; Tail recursion demonstration
;; The idea is to develop two recursive procedures 
;;  that do the same work, except that one
;;  uses tail recursion and the other doesn't
;;  We force the recursion to an excessive depth and
;;  watch the non tail recursive procedure die 
;;  due to insufficient stack space, while the other
;;  one can complete.

;; no tail recursion
(define (func1 x)
  (if (= x 0)
	  0
	  (+ x (func1 (- x 1)))))

;; tail recursion
(define (func2 x sum)
	(if (= x 0)
		sum
		(func2 (- x 1) (+ sum x))))

(define big (expt 2 15))
(func1 big)
(func2 big 0)