TODO

* Type checker improvements:
  - allow generalization for local bindings
  - use subsumption (like if) in the arms of alternatives
  - instead of skolemization, use regular variables, making sure they are unique
* Redo type synonym expansion
  - Do expansion during unification
* Implement two level tables for instances even in the tricky cases
* Removing [] from prim table
* Use pointer reversal during marking, will be slower
* Fix bug uncovered by Data.Type.Equality
* mkQIdent
* Get rid of evalstring()
  - do everything in Haskell
* Better pretty print of Expr
* Implement qualified constraints
* Use capi, add value and field modifiers
* Ad hoc fix for f.g: check if g is a field
* Divide lib into different packages
* Sync lib with GHC base
* Use finalizers for alloca?
* Better naming of internal identifiers
* Implement hSetBuffering
  Do this by adding a new BFILE type that just buffers:
   NoBuffering      - flush on every character
   LineBuffering    - flush on '\n'
   (BlockBuffering n - accumulate a block before doing a write)
* Using ! on a pattern binding has no effect
* Include package name in full name


Bugs:
* Check for escaping skolemized variables
* Type checking Data.Data
* let needs {} in a do with {}
* export list in -boot doesn't work
* polykinded signatures don't work properly, e.g., ~
  there is no place to put the forall
* tr :: forall t -> Typeable t => TypeRep
  tr a = typeRep (Proxy :: Proxy a)
* cannot parse (a -> b) as an expression

Wishlist:
* DeriveGeneric (claudeha)
    Needs TypeFamilies
* Polymorphic record update (claudeha)