Welcome to DrRacket, version 7.4 [3m].
Language: racket, with debugging [custom]; memory limit: 128 MB.
> (define g (make-stream 1 2 (+ 3 4)))
> (next! g)
1
> (next! g)
2
> (next! g)
7
> (next! g)
'DONE
> (next! g)
'DONE
> (require racket/control)
> shift
. shift: bad syntax in: shift
> (shift hi 8)
8
> (shift hi (+ 5 9))
14
> hi
. . hi: undefined;
 cannot reference an identifier before its definition
> (+ 5 (shift hi 1))
1
> hi
. . hi: undefined;
 cannot reference an identifier before its definition
> (define cont (void))
> (+ 5 (shift hi (begin (set! cont hi) 1)))
1
> cont
#<procedure:...cket/control.rkt:157:23>
> (cont 4)
9
> (cont 3)
8
> (cont 1)
6
> (+ 5 (shift k (k 1))) ; k = (+ 5 _)
6
> (+ 5 (shift k (* (k 1) (k 2))))
42
> (* (k 1) (k 2)) ; k = (+ 5 _)
. . k: undefined;
 cannot reference an identifier before its definition
> (* (+ 5 1) (+ 5 2))
42
> (list (+ 5 (shift k
     (append (k 1) (k 2))))) ; k = (list (+ 5 _))
'(6 7)
> ; (append (k 1) (k 2)) ; where k = (list (+ 5 _))
(append (list (+ 5 1)) (list (+ 5 2)))
'(6 7)
> (* (+ 1 (shift k
      (+ (k 5) (k 6))))) ; k = (* (+ 1 _))
13
> (+ (* (+ 1 5)) (* (+ 1 6)))
13
> (* 5)
5
> (define a (* (+ 1 (shift k (+ (k 5) (k 6))))))
. . +: contract violation
  expected: number?
  given: #<void>
  argument position: 1st
  other arguments...:
> ;k = (define a (* (+ 1 _)))
3
3
> (define a (reset (* (+ 1 (shift k (+ (k 5) (k 6)))))))
> a
13
> (reset (* 3 4))
12
> ;what does k represent in:
; (reset (* 10 (+ 2 (shift k (* (k 3) (k 4))))))
; Answer: k = (* 10 (+ 2 _))

; (* (k 3) (k 4)) ; where k = (* 10 (+ 2 _))
; (* (* 10 (+ 2 3)) (* 10 (+ 2 4)))
; (* 50 60)
(reset (* 10 (+ 2 (shift k (* (k 3) (k 4))))))

3000
> 
; (* 10 (reset (+ 2 (shift k (* (k 3) (k 4))))))
; k = (+ 2 _)

; (* 10 (* (k 3) (k 4)))
; (* 10 (* (+ 2 3) (+ 2 4)))
; (* 10 (* 30))
; 300
(* 10 (reset (+ 2 (shift k (* (k 3) (k 4))))))
300
> 
; (* 10 (+ 2 (reset (shift k (* (k 3) (k 4))))))
; k = _

; (* 10 (+ 2 (* (k 3) (k 4))))
; (* 10 (+ 2 (* 3 4)))
; (* 10 (+ 2 12))
; 140
(* 10 (+ 2 (reset (shift k (* (k 3) (k 4))))))
140
>