A simple example of call/cc (call-with-current-continuation)

call-cc.scm

(define (g x)
  (display "萬歲")
  (cos (x 18))(x 20)
  (display "ura")
  72
)
(call-with-current-continuation g)
;; prints 萬歲; then returns 18

 (g cos)
(define
  (h x)
  (display "萬歲")
  (cos (x 18))
  (x 20)
  (display "ura")
  72
  (+ 2 2)
)
(h cos)
;;prints 萬歲ura; returns 4 4

(define (j x)
  (display "萬歲")(cos (x 18))(x 20)
  (display "ura")
  72
  (call-with-current-continuation j))
(j cos)
;; prints 萬歲ura萬歲; returns 18

(define c #f)
(define k #f)
(define a 5)
(define n 0)
(call-with-current-continuation (lambda (kk)(
  (let foo ()
    (if (= a 5)
      (begin (+ 7 
              (/ 5 (call-with-current-continuation
                     (lambda (cc)
                       (set! c cc)
                       (set! k kk)
                       (k 6)))))
            (display "cat\n")
            (display n)
            (set! n (+ n 1))
            (set! a 3)
            (foo))
      (begin (display "123\n")(foo))))
)))
; -> returns 6

(c 12)
; -> prints
;cat
;0123
;123
;123
;...