Path: utzoo!attcan!uunet!cs.utexas.edu!asuvax!noao!arizona!gudeman
From: gudeman@cs.arizona.edu (David Gudeman)
Newsgroups: comp.lang.misc
Subject: Re: Pointers are abstractions
Message-ID: <26376@megaron.cs.arizona.edu>
Date: 14 Oct 90 06:35:09 GMT
Organization: U of Arizona CS Dept, Tucson
Lines: 51

In article  <65671@lanl.gov> jlg@lanl.gov (Jim Giles) writes:
]Congratulations.  You've reinvented a variation of one of the standard
]ways to describe pointers abstractly.

What has been will be again,
What has been done will be done again;
There is nothing new under the sun.
				-- the words of the Teacher

]You missed the point the other person was making though.  Of course

The person said "pointers are about memory".  That is wrong.  Pointers
are not about memory, they are about sequences (though the idea can
usefuly be extended to non-linear data as well).

]pointers can be described mathematically - a computer is a formal
]system: EVERYTHING on it can be formalized mathematically.  That's
]not the issue.

No, you missed _my_ point.  It is not that pointers can be described
mathematically, it is that pointers are abstract objects.  Many of
your objections to pointers seem to be related to your mistaken idea
that pointers are no more than a way to get at machine addresses.
If pointers were no more than that, then I might agree that they do
not belong in high-level languages.

]  The question is: do you ever have to introduce
]pointers into the semantic description of anything _else_?  The
]almost universal answer is NO.

When did that become the question?  I thought the statement (not the
question) was that "pointers are not good for anything".

(and as long as I am combining articles today)

]In fact, the language I'm
]co-designing probably _will_ eventually have pointers (at least, if
]it ever developes that far).  I have pointed this out to Dan
]numerour times in past correspondence: yet another thing he
]consistently has chosen to ignore.

Well this was a well-kept secret from me.  All I ever saw was this
Type-A-personality attitude that pointers are Evil and should never be
used by Right-Thinking Programmers.  If all this heat and noise is
based on a misunderstanding I'm a little embarrassed, but I can only
read what's written there in the article.
-- 
					David Gudeman
Department of Computer Science
The University of Arizona        gudeman@cs.arizona.edu
Tucson, AZ 85721                 noao!arizona!gudeman