chibi-scheme/lib/srfi/1/deletion.scm
Alex Shinn 8b5eb68238 File descriptors maintain a reference count of ports open on them
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.
2014-02-20 22:32:50 +09:00

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852 B
Scheme

;; deletion.scm -- list deletion utilities
;; Copyright (c) 2009-2012 Alex Shinn. All rights reserved.
;; BSD-style license: http://synthcode.com/license.txt
(define (delete x ls . o)
(let ((eq (if (pair? o) (car o) equal?)))
(if (eq? eq eq?)
(let lp ((ls ls) (rev '())) ;; fast path for delq
(let ((tail (memq x ls)))
(if tail
(lp (cdr tail) (take-up-to-reverse ls tail rev))
(if (pair? rev) (append-reverse! rev ls) ls))))
(remove (lambda (y) (eq x y)) ls))))
(define delete! delete)
(define (delete-duplicates ls . o)
(let ((eq (if (pair? o) (car o) equal?)))
(let lp ((ls ls) (res '()))
(if (pair? ls)
(lp (cdr ls) (if (member (car ls) res eq) res (cons (car ls) res)))
(reverse! res)))))
(define delete-duplicates! delete-duplicates)