[m-rev.] for review: list__sort_and_remove_equivs/3

[Mark Brown]

On 05-Sep-2002, Mark Brown <dougl at cs.mu.OZ.AU> wrote:
> Hi,
> 
> This is for review by Fergus.  I was motivated to make this change
> because of a bug I introduced (and then fixed) in the ICFP submission;
> I expected list__sort_and_remove_dups/3 to behave the way that
> list__sort_and_remove_equivs/3 now does.
> 
> Cheers,
> Mark.
> 
> Estimated hours taken: 0.5
> Branches: main
> 
> library/list.m:
> 	Add list__sort_and_remove_equivs/3, which is the same as
> 	list__sort_and_remove_dups/3 except that we use the equivalence
> 	relation implied by the comparison predicate, instead of the usual
> 	equality.
> 
> 	Clarify the existing comment on list__sort_and_remove_dups/3, to
> 	make it clear what its behaviour is.
> 
> tests/hard_coded/Mmakefile:
> tests/hard_coded/sort_and_remove_dups.exp:
> tests/hard_coded/sort_and_remove_dups.m:
> 	A test case for list__sort_and_remove_{dups,equivs}/3.
> 

Actually, I've just thought of a potential problem with this change.  The
problem is that if list__sort is not stable, then the output of the new
predicate is not well defined (that is, there would be more than one
solution that fits the specification).  Is list__sort meant to be stable?

Cheers,
Mark.

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