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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.
34 lines
656 B
Scheme
34 lines
656 B
Scheme
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(define fail
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(lambda () 999999))
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(define in-range
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(lambda (a b)
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(call-with-current-continuation
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(lambda (cont)
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(enumerate a b cont)))))
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(define enumerate
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(lambda (a b cont)
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(if (< b a)
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(fail)
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(let ((save fail))
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(begin
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(set! fail
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(lambda ()
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(begin
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(set! fail save)
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(enumerate (+ a 1) b cont))))
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(cont a))))))
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(write
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(let ((x (in-range 2 9))
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(y (in-range 2 9))
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(z (in-range 2 9)))
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(if (= (* x x)
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(+ (* y y) (* z z)))
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(+ (* x 100) (+ (* y 10) z))
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(fail))))
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(newline)
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