Proposal: unify constant functors

[Henning Thielemann]

On Thu, 3 May 2012, wren ng thornton wrote:

> Indeed. I'm fine with Const (we don't call the value-level function k, 
> afterall), but Constant is just too much. Ditto for the excessively lengthy 
> naming of the identity functor. For things this basic and this widely used, 
> all that verbosity gives me flashbacks to coding in Java.

It's not all bad in imperative languages ...

Do you really use "Identity" everywhere? I use it only implicitly as part 
of transformers:State monads and friends.

Identity's meaning is immediately clear. 'Ident' or 'Id' could also be 
'identifier'.

'Const' could also mean 'constructor'.

I also prefer 'Integer' to \mathbb{Z} and 'Rational' to \mathbb{Q}.