Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!yale!cmcl2!kramden.acf.nyu.edu!brnstnd
From: brnstnd@kramden.acf.nyu.edu (Dan Bernstein)
Newsgroups: comp.lang.misc
Subject: Re: C's sins of commission
Message-ID: <5094:Nov1405:55:1990@kramden.acf.nyu.edu>
Date: 14 Nov 90 05:55:19 GMT
References: <27376@megaron.cs.arizona.edu> <-M.6315@xds13.ferranti.com>
Organization: IR
Lines: 36

In article <-M.6315@xds13.ferranti.com> peter@ficc.ferranti.com (Peter da Silva) writes:
> Piercarlo Grandi:
> > ]Ah no, this cannot pass. Lists and trees are *implementations*, and when
> > ]you draw them you draw specific encodings of such implementations.
> David Gudeman:
> > No, this cannot pass.  Lists and trees are mental structures that
> > humans use to visualize things.
> While I'm generally in the bit-bangers camp, I must agree with Piercarlo here.
> The basic things that people work with are "chunks of data". Lists, trees,
> tries, and so on are methods of implementing these databases in efficient
> ways. There's nothing fundamental about them.

I am in the bit-bangers camp and must agree with Dave here. Although it
would be nice to imagine the computer as accepting some abstract,
mathematical version of what I wanted to compute and spitting out some
results, that's not how it works on the lowest levels, or on any level
showing any efficiency.

I am translating a computation into a form that a machine can
understand. That final form may not be ``fundamental,'' but it *is* the
mental structure that I have to work with. In real programming, I find
myself working with a form that includes arrays and pointers and so on.
So those are the mental structures I deal with. That's why I think Dave
is right.

If I didn't care about finishing anything, I might use a functional
language. (Actually, I shouldn't be nasty---I hear SETL is becoming
rather efficient after all these years. It's imperative, but it has a
lot of the structures Jim seems to love.) So the final form I worked
with might include some more abstract type, and I'd probably agree more
with Piercarlo that relations and trees are higher level than pointers
and arrays.

Can we all agree to disagree now?

---Dan