30 lines
867 B
Scheme
30 lines
867 B
Scheme
;; Copyright 2000 Lars T Hansen
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;; SPDX-License-Identifier: MIT
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#!r6rs
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(library (srfi srfi-15)
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(export fluid-let)
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(import (rnrs))
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(define-syntax fluid-let
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(syntax-rules ()
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((_ ((v1 e1) ...) b1 b2 ...)
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(fluid-let "temps" () ((v1 e1) ...) b1 b2 ...))
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((_ "temps" (t ...) ((v1 e1) x ...) b1 b2 ...)
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(let ((temp e1))
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(fluid-let "temps" ((temp e1 v1) t ...) (x ...) b1 b2 ...)))
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((_ "temps" ((t e v) ...) () b1 b2 ...)
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(let-syntax ((swap!
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(syntax-rules ()
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((swap! a b)
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(let ((tmp a))
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(set! a b)
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(set! b tmp))))))
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(dynamic-wind
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(lambda ()
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(swap! t v) ...)
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(lambda ()
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b1 b2 ...)
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(lambda ()
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(swap! t v) ...)))))))
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