Path: utzoo!mnetor!uunet!seismo!sundc!pitstop!sun!quintus!ok
From: ok@quintus.UUCP (Richard A. O'Keefe)
Newsgroups: comp.lang.prolog
Subject: Re: BSI Prolog terms of reference
Message-ID: <883@cresswell.quintus.UUCP>
Date: 16 Apr 88 07:43:49 GMT
References: <831@cresswell.quintus.UUCP> <249@gould.doc.ic.ac.uk> <256@gould.doc.ic.ac.uk>
Organization: Quintus Computer Systems, Mountain View, CA
Lines: 125
Keywords: promises

In article <256@gould.doc.ic.ac.uk>, cdsm@ivax.doc.ic.ac.uk (Chris Moss) writes:
> Unfortunately, since the breakup of the original Edinburgh group centred 
> round the DEC10 implementation there has really been no coherence at all.
> Poplog, NIP, Prolog-X all come from the right stable but vary in many
> details. To those further afield it is even more confusing.

This is, um, misleading.  The last version of PopLog I used was *VERY*
close to DEC-10 Prolog (so much so that porting the DEC-10 Prolog library
to it was a matter of taking the C-Prolog version I had and undoing most
of the changes I had made to the DEC-10 version to get the C-Prolog version).
In 1984, which is the last time I saw it, Prolog-X was as close to DEC-10
Prolog as, say, SB Prolog.  NIP was written at Edinburgh to be used by
people at Edinburgh, who were worried by the fact that the DEC-10 was
going away and didn't want to rewrite a lot of code.  I have a manual for
NIP that is a couple of years old; at that time it was _very_ close to
DEC-10 Prolog.

Each of these three dialects that Chris Moss mentions is or contains a
sublanguage which is _very_ close to DEC-10 Prolog; about as close as
C Prolog or ALS Prolog.  They are ***MUCH*** closer to each other than
any of them is to the current BSI fragments.  Dash it all, if it comes
to that, the "Edinburgh-compatible" aspect of LPA MacProlog is a whale
of a lot closer to this common core than it is to the BSI fragments.

> >It is very easy to deny that the early work was based on Edinburgh Prolog:
> >some of the early stuff looked uncommonly like Sigma Prolog.
 
> I work in the same establishment as the authors of SigmaProlog.
> I'm not going to start badmouthing them on the net.

How is admitting that some of the early stuff looked like Sigma Prolog
badmouthing anyone?  The fact that it is very different from Edinburgh
Prolog doesn't mean it's _bad_.

> But really Richard, you do like to have your cake and eat it too.

Please explain!  All I want is a standard which is close to the common
core of Edinburgh Prologs; which is what was originally promised.
Yes, 53, 50, 47, and 54 are not identical, but that is no reason to
give us 23 instead.  How about giving us 51?

> Frank McCabe gave up the chairmanship of the syntax committee last summer
> when all he had produced was principles and sketches, leaving me to
> try to put together a document which was acceptable to all. So for
> the last 9 months I've been trying to do that. Many of his ideas 
> are worth listening to and some of them have problems. But when all
> sides adopt a dog in the manger attitude one will never get anywhere.

What has Frank McCabe to do with anything?  I hope nobody has taken anything
I have written in this forum as an attack on Chris Moss:  the BSI committee
decided what sort of grammar they wanted and that's the kind Chris Moss has
to produce.  He makes a great tailor, but if the rest of the committee give
him a sow's ear, the best he can possibly make is a leather purse.

Which sides are adopting a dog-in-the-manger attitude?  (The meaning of
that phrase is that a manger is a box containing fodder for cattle: the
dog lying in it cannot eat it himself and won't let the cattle eat either.)

Look, I'm not interested in who is doing what, whose ideas are good,
whose ideas are bad, who is chairman, or any of that.  What interests me
is that there are a lot of Prolog systems which have a great deal in
common, that there is a Prolog standard being developed, and that this
standard is far more different from any two of those existing systems
than they are from each other.

> Anyway all this is history. It looks as if it's ISO Prolog that will
> get the attention in future. This opens up the field to far more input
> and introduces more problems, too. So PS/69 as well as earlier statements
> are effectively dead as far as I can see. 

What is ISO Prolog?  Which groups are doing the work?  Do people on the
existing BSI mailing list get all the documents relevant to the ISO work?
Which document contains the promises made to ISO?

> I don't object to you arguing for the standard to be based on Quintus.
> You might be considered to be failing your employers if you didn't.
> But don't presume that Quintus is in a uniquely priviledged position.

News for you, chum.  I have ***NEVER*** argued for the standard to be
based on Quintus Prolog.  Sob, sob, I guess I'm failing my employers,
oh the shame.  I have been very very careful to avoid suggesting at
any point that the standard should be based on Quintus Prolog, and in
the documents I wrote at Edinburgh I was explicit in rejecting the
idea that the standard should be based on DEC-10 Prolog.

I am deeply offended that Chris Moss should suggest that I am arguing
for my employers rather than for what is technically good.  Listen, and
listen good:  my perspective on the standard remains the perspective
that I had at Edinburgh:  what do I need in a standard so that I can
write a large, reasonable, useful library, and be able to give it to
anyone with a standard Prolog.  That is, I retain a _user's_ viewpoint,
not an implementor's.  I criticise BSI Prolog because it is just plain
_BAD_, not for any other reason.

Get this clear:  if the BSI/ISO crowd took ALS Prolog and rubber-stamped
it "standard" (if it isn't already clear, I do not work for ALS and have
never received any money from them), that'd be ok by me.  At least it
wouldn't be the disaster that the BSI's philautic changes would be.  The
ideal, of course, would be to have NU Prolog as the standard (:-).
[No, I don't work for Melbourne either.]

I have loaned all my copies of BSI stuff to someone, so I can't quote
the exact wording.  Bear in mind that the BSI standard is already over
two years late, and that I complained about this about a year ago:
	Name pretty well any feature of term output, and the fragments
	do not define it.
For example:
	There is currently nothing in any of the fragments I have received
	that says what base integers are written out in.
This is of interest because there are Prolog systems such as Xerox Quintus
Prolog and ZYX Prolog which are closely coupled with a Lisp system; if the
Lisp system changes its output base, should this affect Prolog code?
Is this nit-picking?  No: at the Prolog Benchmarking Workshop people who
were porting programs from one dialect to another often tried to compare
the output of the original version and the output of the ported version.
When different dialects put spaces in different places, that showed up as
spurious differences.  (Dash it all, I raised _that_ point in late 1984,
in the context of what you need to make a validation suite work.)

    When I complain that the BSI group have wasted their time introducing
differences where the differences were minor and have largely ignored the
differences which _are_ a practical problem, I am not being a dog in the
manger, I am not badmouthing anyone, I am not advocating Quintus Prolog,
I am stating what is obvious to anyone who has seriously tried to port
large programs between one "Edinburgh-compatible" dialect and another.