On Fri, Feb 10, 2012 at 04:03:42PM +0000, Simon Peyton-Jones wrote:
The page describes an improved implementation of the Typeable class, making use of polymorphic kinds. Technically it is straightforward, but it represents a non-backward-compatible change to a widely used library, so we need to make a plan for the transition.
http://hackage.haskell.org/trac/ghc/wiki/GhcKinds/PolyTypeable
This sounds good, but what does it mean for other Haskell implementations? I guess if they implement "deriving Typeable" then most code would continue to work with the old Data.Typeable implementation (well, with some small changes to handle things like the typeOf / typeRep change). But it would be better if they could use the new definition. Is PolyKinds sufficiently well-defined and simple that it is feasible for other Haskell implementations to implement it? By the way, shouldn't this be discussed on libraries@? Thanks Ian