Hello,

On Mon, Feb 13, 2012 at 5:32 PM, Edward Kmett <ekmett@gmail.com> wrote:

There are fewer combinators from commonly used classes for working with the left argument of a bifunctor, however.

I think that the bifunctor part of Bas's version is a bit of a red herring.  What I like about it is that it overloads exactly what needs to be overloaded---the representation of the type---without the need for any fake parameters.  To make things concrete, here is some code:

> newtype TypeRepT t = TR TypeRep

> 

> class Typeable t where

>   typeRep :: TypeRepT t

>

> instacne Typeable Int where typeRep = TR type_rep_for_int

> instance Typeable []  where typeRep = TR type_rep_for_list