Hello, Are there any uses of this instance that are not related to error handing? If not, I would propose that we avoid prolonging the confusing use of "Either" for error handling and define a separate type with properly labelled constructors, to be used as "Maybe" but with multiple reasons for failure. -Iavor On Wed, May 26, 2010 at 4:44 AM, Ross Paterson <ross@soi.city.ac.uk> wrote:
Ashley Yakeley <ashley@semantic.org> writes:
I currently have my own implementations for these:
instance Foldable Identity instance Traversable Identity instance Applicative Identity
The transformers package has such instances (but currently for a different Identity type).
instance Foldable (Either p) instance Traversable (Either p) instance Applicative (Either p)
instance Foldable ((,) p) instance Traversable ((,) p)
The Applicative one is proposed here. The others should also be added. _______________________________________________ Libraries mailing list Libraries@haskell.org http://www.haskell.org/mailman/listinfo/libraries