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
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