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From: lgm@cbnewsc.att.com (lawrence.g.mayka)
Newsgroups: comp.lang.lisp
Subject: Re: FALSE vs empty list
Summary: Common Lisp itself often uses multiple values for this
Message-ID: <1990Sep7.004222.26947@cbnewsc.att.com>
Date: 7 Sep 90 00:42:22 GMT
References: <24305@uflorida.cis.ufl.EDU> <119011@linus.mitre.org> <35036@unix.cis.pitt.edu>
Organization: AT&T Bell Laboratories
Lines: 16

> Another possible scheme is to return a dotted pair, in which the first
> value is t or nil, depending on the success of the match, and the
> second value is the list of sustitutions.
> 
> This is the way that _Common_LISPcraft_ by Robert Wilensky does it.

Common Lisp functions often return two values in this situation: the
result (if any), and an indication of success or failure.  SUBTYPEP is
a typical example.


	Lawrence G. Mayka
	AT&T Bell Laboratories
	lgm@iexist.att.com

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