[m-dev.] documentation for pragma fact_table

[Zoltan Somogyi]

David Matthew OVERTON wrote:
> Added documentation for `pragma fact_table's to the user guide and
> reference manual.  The additions are commented out at the moment.

Fergus wrote:
> My view is that `pragma fact_table' should not be part of the language,
> but should instead be considered as an implementation-specific extension.
> Hence, it should be documented in the user's guide, not in the language
> reference manual.
> 
> However, the language reference manual should be modified to say that
> implementations may add implementation-specific pragmas.

I agree with Fergus that `pragma fact_table' should not be part of Mercury.
However, pragmatically what people look for in the reference manual is what
the current "mc" can compile. I propose that we add a new section to the
language reference manual on implementation-specific extension, and mention
the ones supported by mc (i.e. pragma fact_table).

Zoltan.