This came up last year, and again recently. The consensus came through to add them, and recently I believe I was nominated to put together a patch. I've just not been able to abrogate my other responsibilities long enough to break my build environment and set up a copy of HEAD and concoct a patch. ;) The instances really have to live in Data.Foldable and Data.Traversable with the Foldable and Traversable classes otherwise you get messy orphan issues. -Edward On Wed, Oct 10, 2012 at 12:04 PM, Merijn Verstraaten <merijn@inconsistent.nl
wrote:
I noticed (to my great dismay!) that ((,) a) doesn't appear to have Foldable or Traversable instance anywhere, even though it is an (almost trivial) instance of both:
instance Foldable ((,) a) where foldMap f (_, x) = f x
instance Traversable ((,) a) where traverse f (a, x) = (,) a <$> f x
I guess the most appropriate place for either would be Data.Tuple of Data.Foldable and Data.Traversable respectively.
Kind regards, Merijn Verstraaten _______________________________________________ Libraries mailing list Libraries@haskell.org http://www.haskell.org/mailman/listinfo/libraries