[m-dev.] parallel conjunction

[Peter Ross]

On Wed, Sep 27, 2000 at 07:18:40AM -0700, Ralph Becket wrote:
> >From Fergus Henderson on 27/09/2000 15:08:06
> > 
> > Another alternative would be to document `&' as a standard feature
> > equivalent to `,' with no additional restrictions on modes or
> > determinism -- just a hint to the implementation to try parallelizing
> > things here.  The implementation would then have to issue warnings
> > rather than errors if its implementation-specific restrictions are not
> > met, and to treat such parallel conjunctions which don't meet its
> > restrictions as if they were ordinary conjunctions.
> 
> This one sounds about right to me.
> 
> > The disadvantage of this approach is that it would require changes
> > to the current implementation, and that you'd only get warnings
> > rather than errors.  The advantage is that it would ensure portability
> > of programs using parallel conjunction to implementations (or grades ;-)
> > that don't support real parallelism.
> 
> How much of a change to the current implementation would be required?
> This parallel conjunction hint is rather like promise declarations - the
> compiler is free to take advantage of it if it feels it can do so, otherwise
> it has no effect.  On this basis, I'd rather go with option no. 3.
> [Btw, do we currently issue warnings about promises the compiler can't 
> decipher?]
> 
No we don't issue warnings.  Accumulator introductions checks to
see whether or not an assertion has a property or not, rather then
determining when reading the assertion in what properties it implies.

Pete
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