mirror of
https://github.com/ashinn/chibi-scheme.git
synced 2025-05-21 06:39:17 +02:00
25 lines
1,008 B
Text
25 lines
1,008 B
Text
|
|
(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))))))
|