Simulating Coroutines in Scheme

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Simulation of other Paradigms and Continuations - slide 37 : 43

Simulating Coroutines in Scheme

Coroutines can be simulated in Scheme by (heavy) use of continuations

Upon resuming C2 from C1
- Activate a continuation cont2 in C2 - pass some value v
- Also send the current continuation cont1 of the resume point in C1
- C2 receives an aggregate consisting of: (v , cont1)

; In C1:
(let ((v ...)           ; value to C2
      (cont2 ...)       ; continuation in C2
     )
  (let ((from-c2        ; value from C2 - received upon the next resume from C2
          (call-with-current-continuation
             (lambda (cont1)              ; captured continuation in C1
                 (cont2 (cons v cont1))   ; resume C2 - pass v and cont1 
             ))))
    ...                                     
  )
)