[m-dev.] for review: remove Prolog support

[Fergus Henderson]

On 11-Mar-1999, Peter Schachte <schachte at cs.mu.OZ.AU> wrote:
> > I asked about removing the Prolog support a while ago, and got no
> > objections, so here is the change to do exactly that.
> > If anyone has any objections to this, now is the time to 
> > mention them...
> 
> I don't have any objection, however I think it's good form in such
> things to warn ahead of time that support will be removed.  E.g.,
> mention in the NEWS file for one release that such support will be
> removed in the next release, and then remove it in the next release.

I think that that is a good general policy.

However, in this particular case, I think it is best to just remove
the feature now.  The reasons are

	(1) The feature is already broken: in particular, it doesn't work
	    with the latest versions of SICStus Prolog.  It's probably
	    not worth the effort of us fixing that if we're just going to
	    drop it in the next release.

	(2) The maintenance cost of the feature is high
	    (every time you add a new library predicate implemented
	    as `pragma c_code' or make a new library predicate
	    builtin, you need to update the Prolog code; also testing
	    the Prolog support chews up a lot of CPU cycles and disk space),
	    and so maintaining it for even one release would be
	    costly.

	(3) It's an implementation feature rather than a language feature,
	    so we're not going to break anyone's programs by removing
	    support for it.  (We might break their Mmakefiles or other
	    scripts, but that is less severe.)

	(4) The chances are very likely that no-one really depends on it.

	(5) The worst-case scenario is really not that bad: even if people do
	    depend on it, they can use the new release and still stick with
	    using the Prolog support from 0.8 until they have fixed their
	    scripts, just by keeping both installations around and
	    setting their PATH appropriately (I will explain this in
	    the NEWS file).

-- 
Fergus Henderson <fjh at cs.mu.oz.au>  |  "I have always known that the pursuit
WWW: <http://www.cs.mu.oz.au/~fjh>  |  of excellence is a lethal habit"
PGP: finger fjh at 128.250.37.3        |     -- the last words of T. S. Garp.