[m-dev.] diff: remove support for cuts

[Fergus Henderson]

On 28-Mar-2000, Zoltan Somogyi <zs at cs.mu.OZ.AU> wrote:
> On 28-Mar-2000, Fergus Henderson <fjh at cs.mu.OZ.AU> wrote:
> > That change breaks backwards compatibility.  You should not remove it, you
> > should instead add a `pragma obsolete' declaration for it, and then wait a
> > couple of releases before removing it.  This change should be mentioned in the
> > NEWS file.
> > 
> > Also the ! predicate might still be useful for people converting Prolog code
> > to Mercury, so I suggest that it be moved to library/prolog.m rather than
> > being removed altogether.
> 
> These two suggestions are not fully compatible: if ! is moved to
> library/prolog.m, people will have to add :- import_module prolog to their
> code.

Actually I meant that you should add it to `library/prolog.m',
and leave the copy in builtin.m, just adding `pragma obsolete' to it.
But now that I think about it, that won't work, since any module
importing `prolog.m' will also import `builtin.m' and so you would
have to use an explicit module qualifier to resolve the ambiguity...

It would be nice if we had something like Ada's `renames',
so that the compiler could detect that the two different occurrences
of `!' were both the same, and thus avoid the ambiguity.

However, since we don't, I guess it is probably best to just
deprecate the existing version in builtin.m (i.e. add the
`pragma obsolete'), and not add it to prolog.m.

-- 
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.
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