Path: utzoo!utgpu!attcan!uunet!husc6!mailrus!purdue!decwrl!labrea!polya!caron
From: caron@polya.Stanford.EDU (Ilan G. Caron)
Newsgroups: comp.lang.lisp
Subject: Re: LET vs. &aux
Message-ID: <5727@polya.Stanford.EDU>
Date: 19 Dec 88 01:40:04 GMT
References: <4400007@uicslsv>
Reply-To: caron@polya.Stanford.EDU (Ilan G. Caron)
Organization: Stanford University
Lines: 18

In article <4400007@uicslsv> bharat@uicslsv.cs.uiuc.edu writes:
>
>I am concerned with the relative efficiencies of using &aux and let
>for using local variables (I usually use whichever seems to be more
>aesthetically appropriate)...
>
First of all, the semantics of an &AUX is identical to a LET* not a
LET.  Secondly, I think that your use of aesthetics is entirely the best
metric in these circumstances.

I suspect that most compilers simply transform the &AUX parameter list
into an equivalent LET* (wrapping the function body) so that in compiled
code, there is no efficiency issue to speak of.

The question is: why does &AUX even exist? is this another throwback
to Mac/Inter/Zeta-Lisp? (I'm sure that Scheme wouldn't be caught dead 
with the extra verbiage).

--ilan