X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2Ftypes%2FTyCon.lhs;h=c495ebb425e7c17575a01b837a05ebb646e6697a;hb=219f900f4e518e8158807cdda6fdec8331f701f0;hp=e1cf3f2269fb78d51e4c671f3c8baf72dcedff14;hpb=17b297d97d327620ed6bfab942f8992b2446f1bf;p=ghc-hetmet.git

diff --git a/compiler/types/TyCon.lhs b/compiler/types/TyCon.lhs
index e1cf3f2..c495ebb 100644
--- a/compiler/types/TyCon.lhs
+++ b/compiler/types/TyCon.lhs
@@ -6,11 +6,11 @@
 The @TyCon@ datatype
 
 \begin{code}
-{-# OPTIONS_GHC -w #-}
+{-# OPTIONS -w #-}
 -- The above warning supression flag is a temporary kludge.
 -- While working on this module you are encouraged to remove it and fix
 -- any warnings in the module. See
---     http://hackage.haskell.org/trac/ghc/wiki/WorkingConventions#Warnings
+--     http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#Warnings
 -- for details
 
 module TyCon(
@@ -33,7 +33,7 @@ module TyCon(
 	isEnumerationTyCon, isGadtSyntaxTyCon, isOpenTyCon,
 	assocTyConArgPoss_maybe, isTyConAssoc, setTyConArgPoss,
 	isTupleTyCon, isUnboxedTupleTyCon, isBoxedTupleTyCon, tupleTyConBoxity,
-	isRecursiveTyCon, newTyConRep, newTyConRhs, newTyConCo_maybe,
+	isRecursiveTyCon, newTyConRhs, newTyConEtadRhs, newTyConCo_maybe,
 	isHiBootTyCon, isSuperKindTyCon,
         isCoercionTyCon_maybe, isCoercionTyCon,
         isImplicitTyCon,
@@ -250,31 +250,20 @@ data AlgTyConRhs
 				--  = the representation type of the tycon
 				-- The free tyvars of this type are the tyConTyVars
       
-        nt_co :: Maybe TyCon,   -- The coercion used to create the newtype
+        nt_co :: Maybe TyCon,   -- A CoercionTyCon used to create the newtype
                                 -- from the representation
-                                -- optional for non-recursive newtypes
+                                -- Optional for non-recursive newtypes
 				-- See Note [Newtype coercions]
+				-- Invariant: arity = #tvs in nt_etad_rhs;
+				--	See Note [Newtype eta]
+				-- Watch out!  If any newtypes become transparent
+				-- again check Trac #1072.
 
-	nt_etad_rhs :: ([TyVar], Type) ,
+	nt_etad_rhs :: ([TyVar], Type)
 			-- The same again, but this time eta-reduced
 			-- hence the [TyVar] which may be shorter than the declared 
 			-- arity of the TyCon.  See Note [Newtype eta]
-
-	nt_rep :: Type	-- Cached: the *ultimate* representation type
-			-- By 'ultimate' I mean that the top-level constructor
-			-- of the rep type is not itself a newtype or type synonym.
-			-- The rep type isn't entirely simple:
-			--  for a recursive newtype we pick () as the rep type
-			--	newtype T = MkT T
-			-- 
-			-- This one does not need to be eta reduced; hence its
-			-- free type variables are conveniently tyConTyVars
-			-- Thus:
-			-- 	newtype T a = MkT [(a,Int)]
-			-- The rep type is [(a,Int)]
-			-- NB: the rep type isn't necessarily the original RHS of the
-			--     newtype decl, because the rep type looks through other
-    }			--     newtypes.
+    }
 
 visibleDataCons :: AlgTyConRhs -> [DataCon]
 visibleDataCons AbstractTyCon      	      = []
@@ -333,7 +322,6 @@ data SynTyConRhs
 
 Note [Newtype coercions]
 ~~~~~~~~~~~~~~~~~~~~~~~~
-
 The NewTyCon field nt_co is a a TyCon (a coercion constructor in fact)
 which is used for coercing from the representation type of the
 newtype, to the newtype itself. For example,
@@ -397,6 +385,14 @@ we get:
 	w2 = w1
 And now Lint complains unless Foo T == Foo [], and that requires T==[]
 
+This point carries over to the newtype coercion, because we need to
+say 
+	w2 = w1 `cast` Foo CoT
+
+so the coercion tycon CoT must have 
+	kind:    T ~ []
+ and	arity:   0
+
 
 Note [Indexed data types] (aka data type families)
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -466,6 +462,7 @@ data PrimRep
   | AddrRep		-- a pointer, but not to a Haskell value
   | FloatRep
   | DoubleRep
+  deriving( Eq )
 
 -- Size of a PrimRep, in bytes
 sizeofPrimRep :: PrimRep -> Int
@@ -805,7 +802,7 @@ tcExpandTyCon_maybe, coreExpandTyCon_maybe
 		  Type,			-- Body type (not yet substituted)
 		  [Type])		-- Leftover args
 
--- For the *typechecker* view, we expand synonyms only
+-- For the *typechecker* view, we expand (closed) synonyms only
 tcExpandTyCon_maybe (SynTyCon {tyConTyVars = tvs, 
 			       synTcRhs = SynonymTyCon rhs }) tys
    = expand tvs rhs tys
@@ -859,9 +856,7 @@ tyConFamilySize (AlgTyCon   {algTcRhs = DataTyCon {data_cons = cons}}) =
 tyConFamilySize (AlgTyCon   {algTcRhs = NewTyCon {}})                  = 1
 tyConFamilySize (AlgTyCon   {algTcRhs = OpenTyCon {}})                 = 0
 tyConFamilySize (TupleTyCon {})	 		                       = 1
-#ifdef DEBUG
 tyConFamilySize other = pprPanic "tyConFamilySize:" (ppr other)
-#endif
 
 tyConSelIds :: TyCon -> [Id]
 tyConSelIds (AlgTyCon {algTcSelIds = fs}) = fs
@@ -878,9 +873,9 @@ newTyConRhs :: TyCon -> ([TyVar], Type)
 newTyConRhs (AlgTyCon {tyConTyVars = tvs, algTcRhs = NewTyCon { nt_rhs = rhs }}) = (tvs, rhs)
 newTyConRhs tycon = pprPanic "newTyConRhs" (ppr tycon)
 
-newTyConRep :: TyCon -> ([TyVar], Type)
-newTyConRep (AlgTyCon {tyConTyVars = tvs, algTcRhs = NewTyCon { nt_rep = rep }}) = (tvs, rep)
-newTyConRep tycon = pprPanic "newTyConRep" (ppr tycon)
+newTyConEtadRhs :: TyCon -> ([TyVar], Type)
+newTyConEtadRhs (AlgTyCon {algTcRhs = NewTyCon { nt_etad_rhs = tvs_rhs }}) = tvs_rhs
+newTyConEtadRhs tycon = pprPanic "newTyConEtadRhs" (ppr tycon)
 
 newTyConCo_maybe :: TyCon -> Maybe TyCon
 newTyConCo_maybe (AlgTyCon {algTcRhs = NewTyCon { nt_co = co }}) = co