Hello,
On Mon, Feb 13, 2012 at 5:32 PM, Edward Kmett
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
The two formulations support exactly the same interface (you can define `Proxy` and the proxied `typeRep` in terms of this class) so I wouldn't say that the one is easier to use that the other, but I think that this formulation is slightly simpler because it avoids the dummy parameter to typeRep. -Iavor