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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.
61 lines
2 KiB
Scheme
61 lines
2 KiB
Scheme
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; File: ctak.sch
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; Description: The ctak benchmark
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; Author: Richard Gabriel
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; Created: 5-Apr-85
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; Modified: 10-Apr-85 14:53:02 (Bob Shaw)
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; 24-Jul-87 (Will Clinger)
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; Language: Scheme
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; Status: Public Domain
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; The original version of this benchmark used a continuation mechanism that
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; is less powerful than call-with-current-continuation and also relied on
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; dynamic binding, which is not provided in standard Scheme. Since the
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; intent of the benchmark seemed to be to test non-local exits, the dynamic
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; binding has been replaced here by lexical binding.
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; For Scheme the comment that follows should read:
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;;; CTAK -- A version of the TAK procedure that uses continuations.
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;;; CTAK -- A version of the TAK function that uses the CATCH/THROW facility.
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(define (ctak x y z)
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(call-with-current-continuation
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(lambda (k)
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(ctak-aux k x y z))))
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(define (ctak-aux k x y z)
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(cond ((not (< y x)) ;xy
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(k z))
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(else (call-with-current-continuation
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(ctak-aux
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k
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(call-with-current-continuation
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(lambda (k)
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(ctak-aux k
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(- x 1)
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y
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z)))
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(call-with-current-continuation
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(lambda (k)
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(ctak-aux k
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(- y 1)
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z
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x)))
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(call-with-current-continuation
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(lambda (k)
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(ctak-aux k
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(- z 1)
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x
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y))))))))
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;;; call: (ctak 18 12 6)
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(let ((input (with-input-from-file "input.txt" read)))
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(time (let loop ((n 8) (v 0))
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(if (zero? n)
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v
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(loop (- n 1)
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(ctak 18 12 (if input 6 0)))))))
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