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19 lines
454 B
Scheme
19 lines
454 B
Scheme
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(define-library (scheme lazy)
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(import (chibi))
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(export delay force delay-force make-promise promise?)
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(begin
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(define (make-promise x)
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(delay x)))
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(cond-expand
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(auto-force
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)
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(else
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(begin
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(define (promise? x)
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(and (pair? x)
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(null? (cdr x))
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(pair? (car x))
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(or (eq? #t (caar x))
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(and (eq? #f (caar x))
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(procedure? (cdar x))))))))))
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