[m-dev.] Re: [HAL-dev] Adding Herbrand types to Mercury

[Fergus Henderson]

On 27-Jan-2004, Ralph Becket <rafe at cs.mu.OZ.AU> wrote:
> Fergus Henderson, Tuesday, 27 January 2004:
> > 
> > Is it a design goal to allow users to implement their own constraint
> > solver for Herbrand-style variables?
> 
> This begs the question, do we want to support combined solver/du types?
> It seems to me that one could simply use combinator functions rather
> than du constructors.  This way the compiler could treat du types,
> solver types and Herbrand/Prolog types entirely separately.

Currently, the drawback with using combinator functions would be
that determinism analysis won't detect switches on mutually exclusive
combinator functions.

However, this is also a problem with any ADTs in Mercury,
so it may be best to solve this by adding support for
declarations that promise these properties, as proposed in
compiler/notes/promise_ex.html.

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