; file: test-show.scm
; author: Robert Keller
; purpose: testing of the "show" wrapper
; For any expression exp 
;     (show exp)
; will print the expression exp and return its value.
; It can thus be wrapped around any expression that is evaluated for a value.

(load "show.scm")

; This version uses the expression as a message

(define (fac1 n)
    (if (< n 1)
        1
        (show (* n (fac1 (- n 1))))))

(fac1 5)


; In this version, show-message, both a message and a value are specified.
; We can use back-quote comma combination, if desired, to get an expression that
; is part literal, part evaluated.

(define (fac2 n)
  (show-message `(fac2 ,n)  ;; back-quote comma convention. The comma specifies to evaluate.
    (if (< n 1)
        1
        (* n (fac2 (- n 1))))))

(fac2 5)


;The output of this program is:
;
;showing value of (* n (fac1 (- n 1))): 1
;showing value of (* n (fac1 (- n 1))): 2
;showing value of (* n (fac1 (- n 1))): 6
;showing value of (* n (fac1 (- n 1))): 24
;showing value of (* n (fac1 (- n 1))): 120
;120
;(fac2 0): 1
;(fac2 1): 1
;(fac2 2): 2
;(fac2 3): 6
;(fac2 4): 24
;(fac2 5): 120
;120