On Fri, 8 Feb 2019, 12:20 am Henning Thielemann, < lemming@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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