[project @ 2001-10-31 15:22:53 by simonpj]

[ghc-hetmet.git] / ghc / compiler / basicTypes / Var.lhs

diff --git a/ghc/compiler/basicTypes/Var.lhs b/ghc/compiler/basicTypes/Var.lhs
index 47d84a3..9545f48 100644 (file)
--- a/ghc/compiler/basicTypes/Var.lhs
+++ b/ghc/compiler/basicTypes/Var.lhs
@@ -14,8 +14,7 @@ module Var (
        tyVarName, tyVarKind,
        setTyVarName, setTyVarUnique,
        mkTyVar, mkSysTyVar, 
-       newMutTyVar, newSigTyVar,
-       readMutTyVar, writeMutTyVar, makeTyVarImmutable,
+       newMutTyVar, readMutTyVar, writeMutTyVar, makeTyVarImmutable,
 
        -- Ids
        Id, DictId,
@@ -27,7 +26,7 @@ module Var (
 
        mkLocalId, mkGlobalId, mkSpecPragmaId,
 
-       isTyVar, isMutTyVar, isSigTyVar,
+       isTyVar, isMutTyVar, mutTyVarDetails,
        isId, isLocalVar, isLocalId,
        isGlobalId, isExportedId, isSpecPragmaId,
        mustHaveLocalBinding
@@ -36,6 +35,7 @@ module Var (
 #include "HsVersions.h"
 
 import {-# SOURCE #-}  TypeRep( Type, Kind )
+import {-# SOURCE #-}  TcType( TyVarDetails )
 import {-# SOURCE #-}  IdInfo( GlobalIdDetails, notGlobalId,
                                IdInfo, seqIdInfo )
 
@@ -84,8 +84,7 @@ data VarDetails
 
   | TyVar
   | MutTyVar (IORef (Maybe Type))      -- Used during unification;
-            Bool                       -- True <=> this is a type signature variable, which
-                                       --          should not be unified with a non-tyvar type
+            TyVarDetails
 
        -- 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.
@@ -198,24 +197,15 @@ mkSysTyVar uniq kind = Var { varName    = name
                     where
                       name = mkSysLocalName uniq SLIT("t")
 
-newMutTyVar :: Name -> Kind -> IO TyVar
-newMutTyVar name kind = newTyVar name kind False
-
-newSigTyVar :: Name -> Kind -> IO TyVar
--- Type variables from type signatures are still mutable, because
--- they may get unified with type variables from other signatures
--- But they do contain a flag to distinguish them, so we can tell if
--- we unify them with a non-type-variable.
-newSigTyVar name kind = newTyVar name kind True
-
-newTyVar name kind is_sig
- = do loc <- newIORef Nothing
-      return (Var { varName    = name
-                 , realUnique = getKey (nameUnique name)
-                 , varType    = kind
-                 , varDetails = MutTyVar loc is_sig
-                 , varInfo    = pprPanic "newMutTyVar" (ppr name)
-                 })
+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
@@ -225,6 +215,9 @@ writeMutTyVar (Var {varDetails = MutTyVar loc _}) val = writeIORef loc val
 
 makeTyVarImmutable :: TyVar -> TyVar
 makeTyVarImmutable tyvar = tyvar { varDetails = TyVar}
+
+mutTyVarDetails :: TyVar -> TyVarDetails
+mutTyVarDetails (Var {varDetails = MutTyVar _ details}) = details
 \end{code}
 
 
@@ -308,7 +301,7 @@ mkGlobalId details name ty info = mkId name ty (GlobalId details) info
 \end{code}
 
 \begin{code}
-isTyVar, isMutTyVar, isSigTyVar                 :: Var -> Bool
+isTyVar, isMutTyVar                     :: Var -> Bool
 isId, isLocalVar, isLocalId                     :: Var -> Bool
 isGlobalId, isExportedId, isSpecPragmaId :: Var -> Bool
 mustHaveLocalBinding                    :: Var -> Bool
@@ -321,8 +314,6 @@ isTyVar var = case varDetails var of
 isMutTyVar (Var {varDetails = MutTyVar _ _}) = True
 isMutTyVar other                            = False
 
-isSigTyVar (Var {varDetails = MutTyVar _ is_sig}) = is_sig
-isSigTyVar other                                 = False
 
 isId var = case varDetails var of
                LocalId _  -> True