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adding srfi-39

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Alex Shinn 2009-12-28 21:05:25 +09:00
parent 02e1bb820d
commit ad068bc1f8
1 changed files with 25 additions and 0 deletions
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lib/srfi/39.module Normal file
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@ -0,0 +1,25 @@
(define-module (srfi 39)
(export make-parameter parameterize)
(import-immutable (scheme))
(body
(define (make-parameter value . o)
(if (pair? o)
(let ((converter (car o)))
(lambda args
(if (null? args)
value
(set! value (converter (car args))))))
(lambda args (if (null? args) value (set! value (car args))))))
(define-syntax parameterize
(syntax-rules ()
((parameterize ("step") ((param value tmp1 tmp2) ...) () body)
(let ((tmp1 value) ...)
(let ((tmp2 (param)) ...)
(dynamic-wind (lambda () (param tmp1) ...)
(lambda () . body)
(lambda () (param tmp2) ...)))))
((parameterize ("step") args ((param value) . rest) body)
(parameterize ("step") ((param value tmp1 tmp2) . args) rest body))
((parameterize ((param value) ...) . body)
(parameterize ("step") () ((param value) ...) body))))))