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https://github.com/ashinn/chibi-scheme.git
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8b5eb68238
They can be close()d explicitly with close-file-descriptor, and will close() on gc, but only explicitly closing the last port on them will close the fileno. Notably needed for network sockets where we open separate input and output ports on the same socket.
50 lines
1.7 KiB
Scheme
50 lines
1.7 KiB
Scheme
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(define-syntax when
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(syntax-rules ()
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((when test . body)
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(if test (begin . body)))))
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(define-syntax unless
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(syntax-rules ()
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((unless test . body)
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(when (not test) . body))))
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(define-syntax guard
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(syntax-rules ()
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((guard (var clause ...) e1 e2 ...)
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((call-with-current-continuation
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(lambda (guard-k)
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(with-exception-handler
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(lambda (condition)
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((call-with-current-continuation
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(lambda (handler-k)
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(guard-k
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(lambda ()
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(let ((var condition)) ; clauses may SET! var
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(guard-aux (handler-k (lambda ()
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(raise-continuable condition)))
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clause ...))))))))
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(lambda ()
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(let ((res (begin e1 e2 ...)))
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(guard-k (lambda () res)))))))))))
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(define-syntax guard-aux
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(syntax-rules (else =>)
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((guard-aux reraise (else result1 result2 ...))
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(begin result1 result2 ...))
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((guard-aux reraise (test => result))
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(let ((temp test))
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(if temp (result temp) reraise)))
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((guard-aux reraise (test => result) clause1 clause2 ...)
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(let ((temp test))
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(if temp (result temp) (guard-aux reraise clause1 clause2 ...))))
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((guard-aux reraise (test))
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(or test reraise))
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((guard-aux reraise (test) clause1 clause2 ...)
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(or test (guard-aux reraise clause1 clause2 ...)))
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((guard-aux reraise (test result1 result2 ...))
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(if test (begin result1 result2 ...) reraise))
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((guard-aux reraise (test result1 result2 ...) clause1 clause2 ...)
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(if test
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(begin result1 result2 ...)
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(guard-aux reraise clause1 clause2 ...)))))
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