X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypes%2FType.lhs;h=9a9fae26085a4dce8e6ed6b3a3eb876e0eaaa263;hb=5b1a5b1e82c9a75f9c657839d8d321822622a1e8;hp=ad7d1c9e0da13a39b741eb1b95ace64e2e0444d0;hpb=e91b5dcbdd7217212110a4bebb6da365ade2d961;p=ghc-hetmet.git

diff --git a/ghc/compiler/types/Type.lhs b/ghc/compiler/types/Type.lhs
index ad7d1c9..9a9fae2 100644
--- a/ghc/compiler/types/Type.lhs
+++ b/ghc/compiler/types/Type.lhs
@@ -18,11 +18,6 @@ module Type (
 	isTypeKind, isAnyTypeKind,
 	funTyCon,
 
-        usageKindCon,					-- :: KX
-        usageTypeKind,					-- :: KX
-        usOnceTyCon, usManyTyCon,			-- :: $
-        usOnce, usMany,					-- :: $
-
         -- exports from this module:
         hasMoreBoxityInfo, defaultKind,
 
@@ -65,7 +60,7 @@ module Type (
 	tidyTopType,   tidyPred,
 
 	-- Comparison
-	eqType, eqKind, eqUsage, 
+	eqType, eqKind, 
 
 	-- Seq
 	seqType, seqTypes
@@ -85,12 +80,12 @@ import {-# SOURCE #-}	PprType( pprType )	-- Only called in debug messages
 import {-# SOURCE #-}   Subst  ( substTyWith )
 
 -- friends:
-import Var	( TyVar, tyVarKind, tyVarName, setTyVarName )
+import Var	( Id, TyVar, tyVarKind, tyVarName, setTyVarName )
 import VarEnv
 import VarSet
 
 import Name	( NamedThing(..), mkInternalName, tidyOccName )
-import Class	( classTyCon )
+import Class	( Class, classTyCon )
 import TyCon	( TyCon, isRecursiveTyCon, isPrimTyCon,
 		  isUnboxedTupleTyCon, isUnLiftedTyCon,
 		  isFunTyCon, isNewTyCon, newTyConRep,
@@ -104,7 +99,7 @@ import CmdLineOpts	( opt_DictsStrict )
 import SrcLoc		( noSrcLoc )
 import PrimRep		( PrimRep(..) )
 import Unique		( Uniquable(..) )
-import Util		( mapAccumL, seqList, lengthIs )
+import Util		( mapAccumL, seqList, lengthIs, snocView )
 import Outputable
 import UniqSet		( sizeUniqSet )		-- Should come via VarSet
 import Maybe		( isJust )
@@ -224,14 +219,11 @@ splitAppTy_maybe :: Type -> Maybe (Type, Type)
 splitAppTy_maybe (FunTy ty1 ty2)   = Just (TyConApp funTyCon [ty1], ty2)
 splitAppTy_maybe (AppTy ty1 ty2)   = Just (ty1, ty2)
 splitAppTy_maybe (NoteTy _ ty)     = splitAppTy_maybe ty
-splitAppTy_maybe (SourceTy p)        = splitAppTy_maybe (sourceTypeRep p)
-splitAppTy_maybe (TyConApp tc [])  = Nothing
-splitAppTy_maybe (TyConApp tc tys) = split tys []
-			    where
-			       split [ty2]    acc = Just (TyConApp tc (reverse acc), ty2)
-			       split (ty:tys) acc = split tys (ty:acc)
-
-splitAppTy_maybe other	     	  = Nothing
+splitAppTy_maybe (SourceTy p)      = splitAppTy_maybe (sourceTypeRep p)
+splitAppTy_maybe (TyConApp tc tys) = case snocView tys of
+					Nothing -> Nothing
+					Just (tys',ty') -> Just (TyConApp tc tys', ty')
+splitAppTy_maybe other	     	   = Nothing
 
 splitAppTy :: Type -> (Type, Type)
 splitAppTy ty = case splitAppTy_maybe ty of
@@ -243,7 +235,7 @@ splitAppTys ty = split ty ty []
   where
     split orig_ty (AppTy ty arg)        args = split ty ty (arg:args)
     split orig_ty (NoteTy _ ty)         args = split orig_ty ty args
-    split orig_ty (SourceTy p)            args = split orig_ty (sourceTypeRep p) args
+    split orig_ty (SourceTy p)          args = split orig_ty (sourceTypeRep p) args
     split orig_ty (FunTy ty1 ty2)       args = ASSERT( null args )
 					       (TyConApp funTyCon [], [ty1,ty2])
     split orig_ty (TyConApp tc tc_args) args = (TyConApp tc [], tc_args ++ args)
@@ -480,7 +472,13 @@ dropForAlls ty = snd (splitForAllTys ty)
 
 -- (mkPiType now in CoreUtils)
 
-Applying a for-all to its arguments.  Lift usage annotation as required.
+applyTy, applyTys
+~~~~~~~~~~~~~~~~~
+Instantiate a for-all type with one or more type arguments.
+Used when we have a polymorphic function applied to type args:
+	f t1 t2
+Then we use (applyTys type-of-f [t1,t2]) to compute the type of
+the expression. 
 
 \begin{code}
 applyTy :: Type -> Type -> Type
@@ -490,17 +488,32 @@ applyTy (ForAllTy tv ty) arg = substTyWith [tv] [arg] ty
 applyTy other		 arg = panic "applyTy"
 
 applyTys :: Type -> [Type] -> Type
-applyTys fun_ty arg_tys
- = substTyWith tvs arg_tys ty
- where
-   (mu, tvs, ty) = split fun_ty arg_tys
-   
-   split fun_ty               []         = (Nothing, [], fun_ty)
-   split (NoteTy _ fun_ty)    args       = split fun_ty args
-   split (SourceTy p)	      args       = split (sourceTypeRep p) args
-   split (ForAllTy tv fun_ty) (arg:args) = case split fun_ty args of
-						  (mu, tvs, ty) -> (mu, tv:tvs, ty)
-   split other_ty             args       = panic "applyTys"
+-- This function is interesting because 
+--	a) the function may have more for-alls than there are args
+--	b) less obviously, it may have fewer for-alls
+-- For case (b) think of 
+--	applyTys (forall a.a) [forall b.b, Int]
+-- This really can happen, via dressing up polymorphic types with newtype
+-- clothing.  Here's an example:
+--	newtype R = R (forall a. a->a)
+--	foo = case undefined :: R of
+--		R f -> f ()
+
+applyTys orig_fun_ty []      = orig_fun_ty
+applyTys orig_fun_ty arg_tys 
+  | n_tvs == n_args 	-- The vastly common case
+  = substTyWith tvs arg_tys rho_ty
+  | n_tvs > n_args 	-- Too many for-alls
+  = substTyWith (take n_args tvs) arg_tys 
+		(mkForAllTys (drop n_args tvs) rho_ty)
+  | otherwise		-- Too many type args
+  = ASSERT2( n_tvs > 0, pprType orig_fun_ty )	-- Zero case gives infnite loop!
+    applyTys (substTyWith tvs (take n_tvs arg_tys) rho_ty)
+	     (drop n_tvs arg_tys)
+  where
+    (tvs, rho_ty) = splitForAllTys orig_fun_ty 
+    n_tvs = length tvs
+    n_args = length arg_tys     
 \end{code}
 
 
@@ -643,8 +656,6 @@ addFreeTyVars ty@(NoteTy (FTVNote _) _)      = ty
 addFreeTyVars ty			     = NoteTy (FTVNote (tyVarsOfType ty)) ty
 \end{code}
 
-
-
 %************************************************************************
 %*									*
 \subsection{TidyType}
@@ -854,7 +865,6 @@ I don't think this is harmful, but it's soemthing to watch out for.
 \begin{code}
 eqType t1 t2 = eq_ty emptyVarEnv t1 t2
 eqKind  = eqType	-- No worries about looking 
-eqUsage = eqType	-- through source types for these two
 
 -- Look through Notes
 eq_ty env (NoteTy _ t1)       t2	  	  = eq_ty env t1 t2