31 lines
564 B
Scheme
31 lines
564 B
Scheme
(define-library (picrin control)
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(import (scheme base))
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; based on paper "Representing Monads" (Filinski 1994)
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(define m #f)
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(define (reset t)
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(call/cc
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(lambda (k)
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(let ((n m))
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(set! m (lambda (r)
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(set! m n)
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(k r)))
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(t)))))
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(define (shift h)
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(call/cc
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(lambda (k)
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(h (lambda (v)
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(reset (lambda ()
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(k v))))))))
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(define prompt reset)
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(define control shift)
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(export shift
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reset
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control
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prompt))
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