32 lines
952 B
Scheme
32 lines
952 B
Scheme
#lang scheme/base
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(require (for-syntax scheme/base)
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(for-template (only-in scheme/base set!)))
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(provide identifier-syntax)
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(define-syntax (identifier-syntax stx)
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(syntax-case stx (set!)
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[(identifier-syntax template)
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#'(...
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(make-set!-transformer
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(lambda (stx)
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(syntax-case stx (set!)
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[(set! . _) (raise-syntax-error
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#f
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"cannot assign to identifier macro"
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stx)]
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[(_ arg ...) #'(template arg ...)]
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[_ #'template]))))]
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[(identifier-syntax
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[id1 template1]
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[(set! id2 pat) template2])
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(and (identifier? #'id1)
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(identifier? #'id2))
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#'(...
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(make-set!-transformer
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(lambda (stx)
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(syntax-case stx (set!)
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[(set! id2 pat) #'template2]
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[(_ arg ...) #'(template1 arg ...)]
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[_ #'template1]))))]))
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