Changes to Typeable

[Simon Peyton-Jones]

|  Should there perhaps be a NewTypeable module which could then be renamed
|  into Typeable once it is sufficiently well established?

I started with that idea, but there would be a 2-stage process:
 * Step 1: (when PolyTypable becomes available) People change to import Data.PolyTypeable
 * Step 2: (when PolyTypeable becomes Typeable) People change back to Data.Typeable

I was hoping to avoid that.  Notice that even if we replace Typeable immediately with the new polymorphic one, doing so has very limited impact: for users who just use "deriving Typeable" and "typeOf", that will work fine with the new thing too.  But I'm sure that some "seams" would show through.  It's a balance.

Simon