[project @ 2001-05-21 09:19:14 by simonpj]

[ghc-hetmet.git] / ghc / compiler / typecheck / TcType.lhs

diff --git a/ghc/compiler/typecheck/TcType.lhs b/ghc/compiler/typecheck/TcType.lhs
index 6e8fc04..3f6831b 100644 (file)
--- a/ghc/compiler/typecheck/TcType.lhs
+++ b/ghc/compiler/typecheck/TcType.lhs
@@ -22,17 +22,18 @@ module TcType (
 
   tcSplitRhoTy,
 
-  tcInstTyVars,
-  tcInstSigVar,
-  tcInstTcType,
+  tcInstTyVar, tcInstTyVars,
+  tcInstSigVars,
+  tcInstType,
 
   --------------------------------
   TcKind,
   newKindVar, newKindVars, newBoxityVar,
 
   --------------------------------
-  zonkTcTyVar, zonkTcTyVars, zonkTcSigTyVars,
+  zonkTcTyVar, zonkTcTyVars, zonkTcTyVarsAndFV, zonkTcSigTyVars,
   zonkTcType, zonkTcTypes, zonkTcClassConstraints, zonkTcThetaType,
+  zonkTcPredType,
 
   zonkTcTypeToType, zonkTcTyVarToTyVar, zonkKindEnv
 
@@ -48,7 +49,7 @@ import Type           ( PredType(..),
                          splitPredTy_maybe, splitForAllTys, 
                          isTyVarTy, mkTyVarTy, mkTyVarTys, 
                          openTypeKind, liftedTypeKind, 
-                         superKind, superBoxity, 
+                         superKind, superBoxity, tyVarsOfTypes,
                          defaultKind, liftedBoxity
                        )
 import Subst           ( Subst, mkTopTyVarSubst, substTy )
@@ -170,26 +171,31 @@ tcInstTyVar tyvar
     in
     tcNewMutTyVar name (tyVarKind tyvar)
 
-tcInstSigVar tyvar     -- Very similar to tcInstTyVar
-  = tcGetUnique        `thenNF_Tc` \ uniq ->
-    let 
-       name = setNameUnique (tyVarName tyvar) uniq
-       kind = tyVarKind tyvar
-    in
-    ASSERT( not (kind == openTypeKind) )       -- Shouldn't happen
-    tcNewSigTyVar name kind
+tcInstSigVars tyvars   -- Very similar to tcInstTyVar
+  = tcGetUniques       `thenNF_Tc` \ uniqs ->
+    listTc [ ASSERT( not (kind == openTypeKind) )      -- Shouldn't happen
+            tcNewSigTyVar name kind 
+          | (tyvar, uniq) <- tyvars `zip` uniqs,
+            let name = setNameUnique (tyVarName tyvar) uniq, 
+            let kind = tyVarKind tyvar
+          ]
 \end{code}
 
-@tcInstTcType@ instantiates the outer-level for-alls of a TcType with
-fresh type variables, returning them and the instantiated body of the for-all.
+@tcInstType@ instantiates the outer-level for-alls of a TcType with
+fresh type variables, splits off the dictionary part, and returns the results.
 
 \begin{code}
-tcInstTcType :: TcType -> NF_TcM ([TcTyVar], TcType)
-tcInstTcType ty
+tcInstType :: TcType -> NF_TcM ([TcTyVar], TcThetaType, TcType)
+tcInstType ty
   = case splitForAllTys ty of
-       ([], _)       -> returnNF_Tc ([], ty)   -- Nothing to do
-       (tyvars, rho) -> tcInstTyVars tyvars            `thenNF_Tc` \ (tyvars', _, tenv)  ->
-                        returnNF_Tc (tyvars', substTy tenv rho)
+       ([],     rho) ->        -- There may be overloading but no type variables;
+                               --      (?x :: Int) => Int -> Int
+                        tcSplitRhoTy rho                       `thenNF_Tc` \ (theta, tau) ->
+                        returnNF_Tc ([], theta, tau)
+
+       (tyvars, rho) -> tcInstTyVars tyvars                    `thenNF_Tc` \ (tyvars', _, tenv)  ->
+                        tcSplitRhoTy (substTy tenv rho)        `thenNF_Tc` \ (theta, tau) ->
+                        returnNF_Tc (tyvars', theta, tau)
 \end{code}
 
 
@@ -208,9 +214,16 @@ tcGetTyVar :: TcTyVar -> NF_TcM (Maybe TcType)
 Putting is easy:
 
 \begin{code}
-tcPutTyVar tyvar ty = UASSERT2( not (isUTy ty), ppr tyvar <+> ppr ty )
-                      tcWriteMutTyVar tyvar (Just ty)  `thenNF_Tc_`
-                     returnNF_Tc ty
+tcPutTyVar tyvar ty 
+  | not (isMutTyVar tyvar)
+  = pprTrace "tcPutTyVar" (ppr tyvar) $
+    returnNF_Tc ty
+
+  | otherwise
+  = ASSERT( isMutTyVar tyvar )
+    UASSERT2( not (isUTy ty), ppr tyvar <+> ppr ty )
+    tcWriteMutTyVar tyvar (Just ty)    `thenNF_Tc_`
+    returnNF_Tc ty
 \end{code}
 
 Getting is more interesting.  The easy thing to do is just to read, thus:
@@ -227,6 +240,11 @@ We return Nothing iff the original box was unbound.
 
 \begin{code}
 tcGetTyVar tyvar
+  | not (isMutTyVar tyvar)
+  = pprTrace "tcGetTyVar" (ppr tyvar) $
+    returnNF_Tc (Just (mkTyVarTy tyvar))
+
+  | otherwise
   = ASSERT2( isMutTyVar tyvar, ppr tyvar )
     tcReadMutTyVar tyvar                               `thenNF_Tc` \ maybe_ty ->
     case maybe_ty of
@@ -266,6 +284,10 @@ short_out other_ty = returnNF_Tc other_ty
 zonkTcTyVars :: [TcTyVar] -> NF_TcM [TcType]
 zonkTcTyVars tyvars = mapNF_Tc zonkTcTyVar tyvars
 
+zonkTcTyVarsAndFV :: [TcTyVar] -> NF_TcM TcTyVarSet
+zonkTcTyVarsAndFV tyvars = mapNF_Tc zonkTcTyVar tyvars `thenNF_Tc` \ tys ->
+                          returnNF_Tc (tyVarsOfTypes tys)
+
 zonkTcTyVar :: TcTyVar -> NF_TcM TcType
 zonkTcTyVar tyvar = zonkTyVar (\ tv -> returnNF_Tc (TyVarTy tv)) tyvar
 
@@ -296,9 +318,9 @@ zonkTcThetaType :: TcThetaType -> NF_TcM TcThetaType
 zonkTcThetaType theta = mapNF_Tc zonkTcPredType theta
 
 zonkTcPredType :: TcPredType -> NF_TcM TcPredType
-zonkTcPredType (Class c ts) =
+zonkTcPredType (ClassP c ts) =
     zonkTcTypes ts     `thenNF_Tc` \ new_ts ->
-    returnNF_Tc (Class c new_ts)
+    returnNF_Tc (ClassP c new_ts)
 zonkTcPredType (IParam n t) =
     zonkTcType t       `thenNF_Tc` \ new_t ->
     returnNF_Tc (IParam n new_t)
@@ -329,7 +351,7 @@ zonkTcTypeToType ty = zonkType zonk_unbound_tyvar ty
        --      Void            if it has kind Lifted
        --      :Void           otherwise
     zonk_unbound_tyvar tv
-       | kind == liftedTypeKind
+       | kind == liftedTypeKind || kind == openTypeKind
        = tcPutTyVar tv voidTy  -- Just to avoid creating a new tycon in
                                -- this vastly common case
        | otherwise
@@ -429,8 +451,8 @@ zonkType unbound_var_fn ty
                             go ty                      `thenNF_Tc` \ ty' ->
                             returnNF_Tc (ForAllTy tyvar' ty')
 
-    go_pred (Class c tys) = mapNF_Tc go tys    `thenNF_Tc` \ tys' ->
-                           returnNF_Tc (Class c tys')
+    go_pred (ClassP c tys) = mapNF_Tc go tys   `thenNF_Tc` \ tys' ->
+                            returnNF_Tc (ClassP c tys')
     go_pred (IParam n ty) = go ty              `thenNF_Tc` \ ty' ->
                            returnNF_Tc (IParam n ty')