X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2FbasicTypes%2FVar.lhs;h=66876c6415deb6c03dd4c782953e7b6eb34d0625;hb=07d4332263895cabac09db76e21ad9c4071011a8;hp=deff82acda7222770ce1dbb87b6bfaa77ed6cb50;hpb=1553c7788e7f663bfc55813158325d695a21a229;p=ghc-hetmet.git

diff --git a/ghc/compiler/basicTypes/Var.lhs b/ghc/compiler/basicTypes/Var.lhs
index deff82a..66876c6 100644
--- a/ghc/compiler/basicTypes/Var.lhs
+++ b/ghc/compiler/basicTypes/Var.lhs
@@ -14,7 +14,7 @@ module Var (
 	tyVarName, tyVarKind,
 	setTyVarName, setTyVarUnique,
 	mkTyVar, mkSysTyVar, 
-	newMutTyVar, readMutTyVar, writeMutTyVar, makeTyVarImmutable, 
+	mkMutTyVar, mutTyVarRef, makeTyVarImmutable, 
 
 	-- Ids
 	Id, DictId,
@@ -41,13 +41,13 @@ import {-# SOURCE #-}	IdInfo( GlobalIdDetails, notGlobalId,
 
 import Name		( Name, OccName, NamedThing(..),
 			  setNameUnique, setNameOcc, nameUnique, 
-			  mkSystemName
+			  mkSystemTvNameEncoded,
 			)
 import Unique		( Unique, Uniquable(..), mkUniqueGrimily, getKey )
 import FastTypes
 import Outputable
 
-import IOExts		( IORef, newIORef, readIORef, writeIORef )
+import DATA_IOREF	( IORef )
 \end{code}
 
 
@@ -85,11 +85,14 @@ data VarDetails
   | TyVar
   | MutTyVar (IORef (Maybe Type)) 	-- Used during unification;
 	     TyVarDetails
+	-- TODO: the IORef should be unboxed here, but we don't want to unbox
+  	-- the Name above.
 
-	-- For a long time I tried to keep mutable Vars statically type-distinct
-	-- from immutable Vars, but I've finally given up.   It's just too painful.
-	-- After type checking there are no MutTyVars left, but there's no static check
-	-- of that fact.
+	-- For a long time I tried to keep mutable Vars statically
+	-- type-distinct from immutable Vars, but I've finally given
+	-- up.  It's just too painful.  After type checking there are
+	-- no MutTyVars left, but there's no static check of that
+	-- fact.
 
 data LocalIdDetails 
   = NotExported	-- Not exported
@@ -195,23 +198,19 @@ mkSysTyVar uniq kind = Var { varName    = name
 			   , varInfo    = pprPanic "mkSysTyVar" (ppr name)
 			   }
 		     where
-		       name = mkSystemName uniq FSLIT("t")
-
-newMutTyVar :: Name -> Kind -> TyVarDetails -> IO TyVar
-newMutTyVar name kind details 
-  = do loc <- newIORef Nothing
-       return (Var { varName    = name
-		   , realUnique = getKey (nameUnique name)
-		   , varType    = kind
-		   , varDetails = MutTyVar loc details
-		   , varInfo    = pprPanic "newMutTyVar" (ppr name)
-		   })
-
-readMutTyVar :: TyVar -> IO (Maybe Type)
-readMutTyVar (Var {varDetails = MutTyVar loc _}) = readIORef loc
-
-writeMutTyVar :: TyVar -> Maybe Type -> IO ()
-writeMutTyVar (Var {varDetails = MutTyVar loc _}) val = writeIORef loc val
+		       name = mkSystemTvNameEncoded uniq FSLIT("t")
+
+mkMutTyVar :: Name -> Kind -> TyVarDetails -> IORef (Maybe Type) -> TyVar
+mkMutTyVar name kind details ref
+  = Var { varName    = name
+	, realUnique = getKey (nameUnique name)
+	, varType    = kind
+	, varDetails = MutTyVar ref details
+	, varInfo    = pprPanic "newMutTyVar" (ppr name)
+	}
+
+mutTyVarRef :: TyVar -> IORef (Maybe Type)
+mutTyVarRef (Var {varDetails = MutTyVar loc _}) = loc
 
 makeTyVarImmutable :: TyVar -> TyVar
 makeTyVarImmutable tyvar = tyvar { varDetails = TyVar}