Path: utzoo!utgpu!watserv1!watmath!att!cbnewsc!lgm
From: lgm@cbnewsc.att.com (lawrence.g.mayka)
Newsgroups: comp.lang.lisp
Subject: Re: Virtues of Lisp syntax (a tangent on macros and Scheme)
Summary: Macros perform compile-time manipulation "behind the scenes"
Message-ID: <1990Sep20.234752.19591@cbnewsc.att.com>
Date: 20 Sep 90 23:47:52 GMT
References: <10466@life.ai.mit.edu> <6217@castle.ed.ac.uk> <10722@life.ai.mit.edu> <1990Sep20.170311@ai.mit.edu>
Organization: AT&T Bell Laboratories
Lines: 26

In article <1990Sep20.170311@ai.mit.edu>, tmb@ai.mit.edu (Thomas M. Breuel) writes:
> * In a language like Scheme (as opposed to CommonLisp)
> that provides efficient implementations of higher order
> constructs with natural syntax, there is little need or
> excuse for something as horrible as LOOP in the first
> place.  

We can talk about Dick Waters' SERIES package instead, if you prefer.
Though functional rather than iterative in style, the SERIES package
still makes heavy use of macros.  Why?  To perform source code
rearrangement during compilation, especially the unraveling of series
expressions into iteration to improve performance.  In general, I see
the primary purpose of macros not as simple syntactic sugar but as a
means of manipulating source code "surreptitiously" at compile time
for reasons of efficiency improvement, tool applicability (e.g.,
recording the source file of a function definition so that Meta-. can
find it on request), existence in the compilation environment (e.g.,
DEFPACKAGE), etc.



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

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