;; prints 'x is zero' otherwise prints x
;; shows off compound statements and basic printing

(define (zero-test x)

  (if (not (= x 0)) 
      (begin
	(display "x is ")
	(display x)
	(newline))
      (begin
	(display "x is zero")
	(newline))))
     
;; t if object is not a list with the exception of the empty list
 
(define (atom? object) (not (pair? object)))

;; simply count number of elements in list

(define (len x) 
  (if (null? x)	0 (+ 1 (len (cdr x)))))

;; recursively count atoms

(define (atomcount x)
  (cond ((null? x) 0)
        ((atom? x) 1)
        (else (+ (atomcount (car x)) (atomcount (cdr x))))))

;; example of cond

(define (type? x)
	(cond ((symbol? x) (display "I am a symbol"))
		     ((number? x) (display "I am a number"))
		     ((boolean? x) (display "I am a boolean"))
		     ((list? x) (display "I am a list"))
	           (else (display "I do not know what I am")))
    (newline) )