[m-dev.] Partial instantiation example in the reference manual.

[Julien Fischer]

Hi Paul,

On Tue, 4 Nov 2014, Paul Bone wrote:

>
> Evan on stackoverflow.com tried the partial instantiation example from the
> reference manual but found that it didn't work.  I tried the same program
> and got the same error.  Is this (part of) the known issue with partial
> instantiation or a seperate bug?  If it is part of the same issue should we
> use a different example in the reference manual or add a note that this
> isn't actually supported by the current implementation?

The language supports it, but the current implementation doesn't due to a
lack of support for aliasing in the mode checker.  Section 3 of this
paper:

     Constraint-based mode analysis of Mercury
     David Overton, Zoltan Somogyi and Peter Stuckey. PPDP'02, Pittsburgh.

has an explanation of *why* the existing mode checker cannot handle that
example.

Cheers,
Julien.