62 lines
1.1 KiB
Scheme
62 lines
1.1 KiB
Scheme
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(define-syntax aif
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(ir-macro-transformer
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(lambda (form inject cmp)
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(let ((it (inject 'it))
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(expr (car (cdr form)))
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(then (car (cdr (cdr form))))
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(else (car (cdr (cdr (cdr form))))))
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`(let ((,it ,expr))
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(if ,it ,then ,else))))))
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(aif (member 'b '(a b c)) (car it) #f)
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;;; test hygiene begin
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(define-syntax mif
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(ir-macro-transformer
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(lambda (form inject cmp)
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(let ((expr (car (cdr form)))
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(then (car (cdr (cdr form))))
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(else (car (cdr (cdr (cdr form))))))
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`(let ((it ,expr))
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(if it ,then ,else))))))
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(let ((if 42))
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(mif 1 2 3))
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; => 2
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(let ((it 42))
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(mif 1 it 2))
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; => 42
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;;; end
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;;; test core syntax begin
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(mif 'a 'b 'c)
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; => b
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(define-syntax loop
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(ir-macro-transformer
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(lambda (expr inject cmp)
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(let ((body (cdr expr)))
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`(call-with-current-continuation
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(lambda (,(inject 'exit))
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(let f ()
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,@body (f))))))))
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(define a 1)
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(loop
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(if (= a 2) (exit #f))
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(set! a 2))
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; => #f
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(loop
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(define a 1)
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(if (= a 1) (exit #f)))
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; => #f
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;;; end
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