Call By Need

"Leo" <leo@fudan.edu>
4 Oct 1999 12:17:25 -0400

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Related articles
Call By Need leo@fudan.edu (Leo) (1999-10-04)
Re: Call By Need derekross@fisheracre.freeserve.co.uk (Derek Ross) (1999-10-06)
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From: "Leo" <leo@fudan.edu>
Newsgroups: comp.compilers
Date: 4 Oct 1999 12:17:25 -0400
Organization: Peking University,Beijing,China
Keywords: practice, functional, comment

Hi,


What is 'Call By Need'? And I'd appreciate if anybody can point to me
some resources that I can learn this topic.


please 'cc' lingu@fudan.edu if possible. thanks,


lin
--
Lin Gu
Computer Science Dept., Peking University
E-mail: lingu@fudan.edu
                  gu_lin@bd748.pku.edu.cn
Web Home:http://lingu.home.chinaren.com/
BP: 010-68478800 X (Shanghai user)161996
                  021-95950 X 161996
[Call by need is halfway between call by name and call by value. The
first time a procedure references a call by need parameter, it evaluates
the parameter and remembers the result, and uses that result for any
subsequent references in the procedure. So if the parameter is never used
at all, it's like call by name in that it's never evaluated, but if it is
used, it's like call by value in that it's evaluated once. -John]

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