[m-rev.] for review: rewrite of Modes chapter

[Fergus Henderson]

On 21-Feb-2003, David Overton <dmo at cs.mu.OZ.AU> wrote:
> On Fri, Feb 21, 2003 at 10:45:07AM +1100, Fergus Henderson wrote:
> > 
> > > +A higher-order inst @var{A} is at least as instantiated as inst @var{B} iff
> > > + at var{A} is identical to @var{B}.
> > > +Higher-order terms are considered ground,
> > > +and there is no way for them to become more ground.
> > 
> > I think this is wrong.  The "is at least as instantiated as" ordering
> > should be the same as the "matches" ordering for higher-order insts.
> > 
> > The compiler is currently still broken regarding this; see
> > <http://www.cs.mu.oz.au/research/mercury/mailing-lists/mercury-reviews/
> > mercury-reviews.0211/0325.html>.
> 
> That email refers to the "matches" ordering.  There are two variants of
> that ordering in the compiler -- inst_matches_initial (which allows
> calls to implied modes) and inst_matches_final (which does not allow
> calls to implied modes).  The implementation of inst_matches_initial is
> currently too convervative.  The implementation of inst_matches_final is
> correct.

I thought the "is at least as instantiated" and "matches" orderings
in Mark's proposed text were corresponding to inst_matches_initial
and inst_matches_final respectively.  If that is not the case, then I
need to review the change again.  Mark, could you please add some "@c"
comments in the TexInfo source clarifying the relationship between these
orderings and the ones in the compiler, and then post a new full diff?

-- 
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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