33 lines
934 B
Scheme
33 lines
934 B
Scheme
(module old-if '#%kernel
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(#%require (for-syntax '#%kernel))
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(#%provide if*)
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(define-syntaxes (if*)
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(lambda (stx)
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(let-values ([(if-stx) (quote-syntax if)])
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(if (pair? (syntax-e stx))
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(let-values ([(l) (syntax->list stx)])
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(if (if l
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(if (= (length l) 3)
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#t
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#f)
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#f)
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(datum->syntax
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stx
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(list if-stx
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(cadr l)
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(caddr l)
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(quote-syntax (void)))
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stx
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stx)
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(datum->syntax
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stx
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(cons if-stx
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(cdr (syntax-e stx)))
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stx
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stx)))
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(datum->syntax
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if-stx
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'if
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stx))))))
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