Add Ord Laws to next Haskell Report

[Oliver Charles]

On Fri, 8 Feb 2019, 12:20 am Henning Thielemann, <
lemming at henning-thielemann.de> wrote:

>
> On Thu, 7 Feb 2019, Andrew Butterfield wrote:
>
> > Imagine trying to define the obvious partial ordering on sets - i.e.
> > subset-or-equal using the Ord class. What should be the result, for
> > Instance Ord (Set Int) of
> >
> > compare (fromList [1]) (fromList [2])    or  fromList [2] <= fromList
> [1] ?
>
> Partial ordering means to me that the comparison function is partial.
> I.e. fromList [2] <= fromList [1] would be "undefined".__________________


Oh heavens no! It's very useful to ask whether two elements are comparable,
that's  a nightmare with this approach.

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