Adding a newtype EndoCategory to Control.Category (ticket #3362)

[Henning Thielemann]

Edward Kmett schrieb:
> As the devil's advocate I'd like to point out that we could just leave
> Endo alone, and define its generalized counterpart separately. No
> worries about TypeSynonymInstances and no hassle.

+1

I don't see a need to give up Endo as it is.

Some of the packages listed by Ross are mine (synthesizer,
synthesizer-core, midi, explicit-exception, special-functor
(compatibility package for GHC-6.4)). I often use Endo as poor man's
diff list implementation.