[m-dev.] adding promise_only_solution

[Fergus Henderson]

On 06-Nov-1998, Peter Schachte <pets at cs.mu.OZ.AU> wrote:
> > > If/when it gets compiler support, then
> > > existing code would continue to work, but new code wouldn't need messy
> > > lambdas and packaging up of multiple outputs.
> > 
> > If/when it gets compiler support, we'll add 
> > 
> > 	:- pragma obsolete(promise_only_solution/1).
> > 
> > of course ;-)
> 
> My point was that if you put it in builtin.m now, if you later build
> it into the compiler in a backward compatible way, then you can
> quietly remove it from builtin.m and existing code won't need to be
> rewritten.

I was thinking that if we add a language builtin, then the syntax
will probably be different: instead of

	promise_only_solution((pred(X::out) is cc_multi :- p(A, X, B)))

I was thinking of having something more like a quantifier

	promise_at_most_one [X] p(A, X, B)

-- 
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"
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