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.