(define x 5)

(define (square x) (* x x))
; try
; (square 12)

; (define sq (lambda (x) (* x x)))

(define (factorial n)
  (if (= n 0) 1
      (* n (factorial (- n 1)))))

; try
; (factorial 100)

(define (hen_na_square x)
     (set! x (* x x))
      x)

(define (bar x)
  (call-with-current-continuation (lambda (k)
    (+ 100 (if (= x 0) 1 (k x))))))

; try
; (bar 0)
; (bar 1)

(define (multlist0 xs)
   (if (null? xs) 1
      (begin
           (display (car xs)) ;
           (display " ")      ;
         (* (car xs) (multlist0 (cdr xs))))))

(define (multlist xs)
   (call-with-current-continuation (lambda (k)
      (define (aux xs)
         (if (null? xs)
	    1
            (if (= 0 (car xs))
               (k 0)
               (begin
                    (display (car xs)) ;
                    (display " ")      ;
                  (* (car xs) (aux (cdr xs)))))))
      (aux xs))))

; try
; (multlist '(1 2 3 4 5 6))
; (multlist '(1 2 3 0 5 6))
; (multlist '(0 2 3 4 5 6))

(define (increase n k)
  (if (> n 10) '()
  (begin (display " i:") (display n)
         (increase (+ n 1) (call-with-current-continuation k)))))

(define (decrease n k)
  (if (< n 0) '()
  (begin (display " d:") (display n)
         (decrease (- n 1) (call-with-current-continuation k)))))

; try
; (increase 0 (lambda (k) (decrease 10 k)))

; (define (yinyang)
;  (let* ((yin
;           ((lambda (cc) (display #\@) cc) (call-with-current-continuation (lambda (c) c))))
;         (yang
;           ((lambda (cc) (display #\*) cc) (call-with-current-continuation (lambda (c) c)))) )
;      (yin yang)))

; don't try -- infinite loop
; (yinyang)