From siponen@amadeus.cs.hut.fi Thu May 19 13:29:19 EDT 1994
Article: 12818 of comp.lang.lisp
Xref: glinda.oz.cs.cmu.edu comp.lang.lisp:12818
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From: siponen@amadeus.cs.hut.fi (Lauri Siponen)
Newsgroups: comp.lang.lisp
Subject: Re: copy-file
Date: 16 May 1994 11:35:07 GMT
Organization: Freenet finland
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Message-ID: <SIPONEN.94May16143508@amadeus.cs.hut.fi>
References: <PCHU.94May12110013@kariba.bbn.com> <2r12bo$bim@underdog.jpl.nasa.gov>
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In-reply-to: ch+@cs.cmu.edu's message of Mon, 16 May 1994 02:15:58 GMT

dpANS introduces some new operations on streams. READ-SEQUENCE and 
WRITE-SEQUENCE allow efficient I/O on files. This version of 
copy-file copies multiple megabyte files easily. I ran it 
on Allegro CL 4.2, SunOS 4.1.3.

(defun copy-file (source target)
  ;; Just an example!
  (with-open-file (in source
		   :direction :input)
    (with-open-file (out target 
		     :direction :output
		     :if-exists :supersede)
      (loop 
	  with buffer = (make-string (* 64 512))
	  for n = (read-sequence buffer in)
	  until (= n 0)
	  do (write-sequence buffer out :end n)))))

READ-SEQUENCE and WRITE-SEQUENCE are not yet supported on every 
Lisp implementation, but if they will be included in Lisp standard, 
their availability should increase.

--
Lauri Siponen, Helsinki University of Technology