Path: utzoo!attcan!uunet!mcsun!ukc!edcastle!aipdc
From: aipdc@castle.ed.ac.uk (Paul D. Crowley)
Newsgroups: comp.lang.functional
Subject: Re: Laziness and Back-to-front Lists
Message-ID: <4289@castle.ed.ac.uk>
Date: 28 May 90 21:28:32 GMT
References: <14531@dime.cs.umass.edu> <2535@skye.ed.ac.uk> <8691@cs.utexas.edu> <4170@castle.ed.ac.uk> <3738@moondance.cs.uq.oz.au>
Reply-To: aipdc@castle.ed.ac.uk (Paul D. Crowley)
Organization: Edinburgh University Computing Service
Lines: 24

WARNING: Uninformed opinions ahead!

I was under the impression that in a truly "pure" functional language
the problem doesn't arise because nothing has more than one argument. 
Things that look as if they should have more than one argument are dealt
with lambda-calculus style:

2+3:  ((plus 2) 3)
(plus 2) means plus applied to two, and equals a function which adds two
to its argument.

so ((plus 2) 3) = (plus2 3) = 5

Under these circumstances you _expect_ order of arguments to be
significant, so it doesn't surprise you that you get different results
if you change it.

I'm trying to imagine a language which evaluated expressions
breadth-first.   Maybe it's already been done?  Obviously your
"done-so-far" structure would be _much_ more complicated than a stack.

-- 
\/ o\ Paul Crowley aipdc@uk.ac.ed.castle
/\__/ "Trust me, I know what I'm doing" - Sledge Hammer