2 Mar
2017
2 Mar
'17
12:06 p.m.
On Thu, Mar 02, 2017 at 05:59:18PM +0100, Andreas Abel wrote:
Ok, Foldable is a formal condition for Traversable, but not actually used in the implementation of Traversable Either. This still leaves room to implement Foldable for Either by
instance Foldable (Either a) where foldMap _ _ = error "Folding Either? Naah, I don't think this is a good idea."
I don't fancy Foldable for Either either, but runtime failures are ugly too.