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original commit: 0680efe7e3013fafccba49a835a6c5b9a3c5527d
This commit is contained in:
Matthew Flatt 2004-08-24 20:52:50 +00:00
parent 49167db7df
commit 933b8ac7c7
1 changed files with 23 additions and 1 deletions
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24
collects/mzlib/stxparam.ss
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@ -73,8 +73,30 @@
;; ----------------------------------------
(require "private/stxparamkey.ss")
(provide syntax-parameter-value)
(provide syntax-parameter-value
make-parameter-rename-transformer)
(define (make-parameter-rename-transformer id)
(make-set!-transformer
(lambda (stx)
(let ([v (syntax-parameter-value (syntax-local-introduce id))])
(cond
[(set!-transformer? v) ((set!-transformer-procedure v) stx)]
[(and (procedure? v)
(procedure-arity-includes? v 1))
(syntax-case stx (set!)
[(set! id _) (raise-syntax-error
#f
"cannot mutate syntax identifier"
stx
#'id)]
[else (v stx)])]
[else
(raise-syntax-error
#f
"bad syntax"
stx
#f)])))))
(define (syntax-parameter-value id)
(let* ([v (syntax-local-value id (lambda () #f))]