Roel Wuyts <wuyts at iam.unibe.ch> wrote:
	PS: I also do quite some Prolog work. And there, as in Smalltalks, it 
	annoys me that my code is not portable between different 
	implementations/vendors...
	
There you are speaking to someone who has experienced the same frustration
and was the first to do anything about it, and is continuing to try to do
something about it.  (The SWI Prolog twiki has a link to the "community
standard" twiki for the library.)  There are some real oddities there.
For example, the BSI Prolog committee was started by someone who claimed
to have asked all the Prolog groups in the UK whether they were interested
in a standard and set it up himself when no-one said yes.  Except he never
asked anyone at Edinburgh, and never asked on the Prolog Digest, and wasn't
aware of the "API standard" I'd circulated on the Prolog Digest and issued
as a technical report.  Then there was the committee member who ran a
company that produced a "Prolog" which, despite its merits, was not, was
never meant to be, and couldn't be, Edinburgh-compatible, yet very nearly
managed to talk the BSI committee into accepting its data structures as the
abstract data structures for BSI Prolog (which was supposed to be based on
Edinburgh Prolog).  Then there was the time when the ISO committee decided
to change some of the most basic operations in the language in a way that
would break every existing program.  And the poor guy who wrote a book
based on the then current draft of the standard, only to find the following
year that it was now dramatically different, so that his book described a
language which had never existed and never did exist.

And what was the basic underlying problem?  Why, a refusal to concede that
users had any rights in the matter:  the language belonged to the committee,
not to anyone who happened to have a body of code written in the language,
and if the committee decided on an incompatible change to the syntax (which
they did, several still remain) then that was just to xxxxing bad for the
lusers.

It's precisely that "we'll change the language any way we like and anyone
who complains is just an obscurantist luser standing in the way of progress"
attitude which seems to be at issue here.

The way the BSI and ISO committees kept on hacking at the language did
_not_ in fact result in great progress being made.  To this day we still
don't have environment/1, which I proposed, having used it to good
effect in porting programs between several different Prolog dialects.
(There's an inferior substitute, prolog_flag, which muddles up
properties of the implementation which can't change and user-assigned
properties which can, and it still doesn't have all the things
environment/1 had.)  To this day we don't have an equivalent of Common
Lisp pathnames, despite me proposing it and offering the Quintus version
as a model (not a constraint).  To this day, the Prolog standard doesn't
include any form of coroutining, so it was obsolete the day it was
issued (and I really can't port the coroutining code I'd written between
the different Prologs available to me that have it, so I don't write
that stuff any more).  To this day, we don't even have the most
elementary foreign function interface in the standard, although there
was for a time a de facto one.  All of these things were obvious needs
back in 1986.

And so it goes.  Stability at the basic language level for Prolog would
*not* have been a barrier to progress.  On the contrary, putzing around
with the language was something the ISO committee did *instead* of progress.

Not every change, not even every well-intentioned change, is progress.
Changes must be examined on their merits, not accepted uncritically
just because they are offered in good faith to address a real problem.