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  1. ; your code goes here
  2.  
  3. ;;Global variable for the continuation
  4. (define k-global #f)
  5.  
  6. ;;We are using let* instead of let so that we can guarantee
  7. ;;the evaluation order
  8. (let* (
  9.        (my-number 3)
  10.        (k
  11.          ;;set bookmark here
  12.          (call-with-current-continuation
  13.            ;;The continuation will be stored in "kont"
  14.            (lambda (kont)
  15.              ;;return the continuation
  16.              kont))))
  17.  
  18.      ;;We are using "my-number" to show that the old stack
  19.      ;;frame is being saved.  When we revisit the continuation
  20.      ;;the second time, the value will remain changed.
  21.      (display "The value of my-number is: ")
  22.      (display my-number)
  23.      (newline)
  24.      (set! my-number (+ my-number 1))
  25.  
  26.      ;;Save the continuation in a global variable.
  27.      (set! k-global k)
  28.      (display "test #2")
  29.      (newline)
  30.      )
  31.  
  32. (display "test#")
  33. (newline)
  34.  
  35. ;;Is "kontinuation" a continuation?
  36. (if (procedure? k-global)
  37.     (begin
  38.        (display "This is the first run, k-global is a continuation")
  39.        (newline)
  40.        ;;Send "4" to the continuation which goes to the bookmark
  41.        ;;which will assign it to "k"
  42.        (k-global 4))
  43.      (begin
  44.        ;;This occurs on the second run
  45.        (display "This is the second run, k-global is not a continuation, it is ")
  46.        (display k-global)
  47.        (newline)))
Success #stdin #stdout 0.03s 4132KB
comments ()
stdin 
Standard input is empty
stdout 
The value of my-number is: 3
test #2
test#
This is the first run, k-global is a continuation
The value of my-number is: 4
test #2
https://ideone.com/qsYp1X
language:
Scheme (guile 2.2.4)
created:
10 years ago
visibility:
public

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