ToDo
~~~~
* Test effect of eta-expanding past (case x of ..)

* Bottom strictness isn't right.  Should be (eg) SSX, not just X.

* Enumeration types in worker/wrapper for strictness analysis

* Use (!) types in data cons to unbox.

* Check constant folding

* .hi file isn't updated if the only change is to the exports.
  For example, UgenAll.lhs re-exports all of U_binding.hs; when a data type
  decl in the latter changes, the .hi file for the former isn't updated.
  I think this happens when a module exports another mdodule thus:

	module UgenAll( module U_binding, ... ) where

* This should be reported as an error:
	data T k = MkT (k Int#)

* Bogus report of overlapped pattern for
	f (R {field = [c]}) = 1
  	f (R {})	      = 2
  This shows up for TyCon.maybeTyConSingleCon

*  > module Main( main ) where

   > f :: String -> Int
   > f "=<" = 0
   > f "="  = 0
   
   > g :: [Char] -> Int
   > g ['=','<'] = 0
   > g ['=']     = 0
   
   > main = return ()
   
   For ``f'' the following is reported.
   
   tmp.lhs:4: 
    Pattern match(es) are overlapped in the definition of function `f'
            "=" = ...

   There are no complaints for definition for ``g''.

* Without -O I don't think we need change the module version
  if the usages change; I forget why it changes even with -O

* Record selectors for existential type; no good!  What to do?
  Record update doesn't make sense either.

  Need to be careful when figuring out strictness, and when generating
  worker-wrapper split.

  Also when deriving.

* Consructor re-use via CSE

		Notes on module dependencies
		~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The Name/Var/Type group is a bit complicated. Here's the deal

	Name, PrimRep, FieldLabel (uses Type.Type)
then
	Var (uses Const.Con, IdInfo.IdInfo, Type.GenType, Type.Kind)
then
	VarEnv, VarSet
then
	Class (uses TyCon.TyCon, Type.Type, SpecEnv.SpecEnv)
then
	TyCon (uses Type.Type, Type.Kind, DataCon.DataCon)
then
	Type (uses [DataCon.DataCon])
then
	DataCon, TysPrim, Unify, SpecEnv, PprType
then
	IdInfo, TysWiredIn (uses DataCon.mkDataCon, [MkId.mkDataConId])
then
	PrimOp (uses PprType, TysWiredIn)
then
	Const (needs PrimOp, [TysWiredIn.stringTy])
then
	Id (needs Const.Con(..)), CoreSyn
then
	CoreUtils, OccurAnal
then
	CoreUnfold (uses OccurAnal)
then
	MkId (uses CoreUnfold)
	

PrimOp uses TysWiredIn


Add
~~~
basicTypes/DataCon.lhs
basicTypes/DataCon.hi-boot

Remove
~~~~~~
specialise/SpecUtils.lhs
basicTypes/IdUtils.lhs