Expected behavior of "deriving Ord"?
Christian.Maeder at dfki.de
Thu Mar 20 14:00:46 EDT 2008
Conal Elliott wrote:
> AddBounds makes total orders from total orders. It just adds new least
> and greatest elements.
> The problem with the derived instance is that it doesn't exploit the
> potential laziness of min on 'a'. Because of their types, min it can
> produce partial info from partial info and (<=) and compares cannot.
Right, I've mixed up partial orders, partial (infinite?) values as input
to total order functions. I could not construct an example, though.
min (NoBound MinBound) (NoBound (NoBound undefined))
worked using ghci.
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