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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.
28 lines
854 B
Scheme
28 lines
854 B
Scheme
;; constructors.scm -- list construction utilities
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;; Copyright (c) 2009-2012 Alex Shinn. All rights reserved.
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;; BSD-style license: http://synthcode.com/license.txt
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(define (xcons a b) (cons b a))
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(define (cons* x . args)
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(let lp ((rev '()) (x x) (ls args))
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(if (null? ls)
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(append-reverse rev x)
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(lp (cons x rev) (car ls) (cdr ls)))))
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(define (list-tabulate n proc)
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(let lp ((n (- n 1)) (res '()))
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(if (< n 0) res (lp (- n 1) (cons (proc n) res)))))
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(define (circular-list x . args)
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(let ((res (cons x args)))
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(set-cdr! (last-pair res) res)
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res))
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(define (iota count . o)
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(let ((start (if (pair? o) (car o) 0))
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(step (if (and (pair? o) (pair? (cdr o))) (cadr o) 1)))
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(let lp ((i count) (res '()))
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(if (<= i 0)
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res
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(lp (- i 1) (cons (+ start (* (- i 1) step)) res))))))
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