On 21.05.2014 00:10, Joachim Breitner wrote:
Am Dienstag, den 20.05.2014, 17:47 -0400 schrieb Edward Kmett:
-1 from me as well, though it is a much softer -1 than on the just breaking everyone silently by changing it.
_Lots_ of users initialize empty maps with mempty
Well, this is another issue, empty should be overloaded via class Empty a where empty :: a but Edward does not like classes without laws.
no problem, let’s replace it with
instance (Ord k) => Monoid (Map k v) where mempty = empty mappend = error "do not use Monoid (Map k v), it is ambiguous"
That should be a compile-time error, please! ;-)
Greetings, Joachim
PS: No, I’m not serious.
-- Andreas Abel <>< Du bist der geliebte Mensch. Department of Computer Science and Engineering Chalmers and Gothenburg University, Sweden andreas.abel@gu.se http://www2.tcs.ifi.lmu.de/~abel/