X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2FbasicTypes%2FVar.lhs;h=4f1ed2e1a603f0ab73b9f710bd5103c1dc44917a;hb=dab87cc9e1269aa7e2e0589e156e024c16b85b1f;hp=cb0a11bace49bc8800913764a0033fe1c4c18b6e;hpb=9221fb31c4207700e9aaf1512e0f73afe487674f;p=ghc-hetmet.git

diff --git a/compiler/basicTypes/Var.lhs b/compiler/basicTypes/Var.lhs
index cb0a11b..4f1ed2e 100644
--- a/compiler/basicTypes/Var.lhs
+++ b/compiler/basicTypes/Var.lhs
@@ -273,8 +273,7 @@ mkTyVar name kind = ASSERT( not (isCoercionKind kind ) )
 
 mkTcTyVar :: Name -> Kind -> TcTyVarDetails -> TyVar
 mkTcTyVar name kind details
-  = -- TOM: no longer valid assertion? 
-    -- ASSERT( not (isCoercionKind kind) )
+  = -- NB: 'kind' may be a coercion kind; cf, 'TcMType.newMetaCoVar'
     TcTyVar {	varName    = name,
 		realUnique = getKeyFastInt (nameUnique name),
 		varType  = kind,
@@ -289,8 +288,8 @@ mkTcTyVar name kind details
 %************************************************************************
 
 \begin{code}
-type CoVar = Var -- A coercion variable is simply a type 
-			-- variable of kind @ty1 :=: ty2@. Hence its
+type CoVar = TyVar -- A coercion variable is simply a type 
+			-- variable of kind @ty1 ~ ty2@. Hence its
 			-- 'varType' is always @PredTy (EqPred t1 t2)@
 
 coVarName :: CoVar -> Name
@@ -311,16 +310,9 @@ mkCoVar name kind = ASSERT( isCoercionKind kind )
 			}
 
 mkWildCoVar :: Kind -> TyVar
--- ^ Create a type variable that is never referred to, so its unique doesn't matter
-mkWildCoVar kind 
-  = ASSERT( isCoercionKind kind )
-    TyVar { varName = mkSysTvName wild_uniq (fsLit "co_wild"),
-            realUnique = _ILIT(1),
-            varType = kind,
-            isCoercionVar = True }
-  where
-    wild_uniq = mkBuiltinUnique 1
-
+-- ^ Create a type variable that is never referred to, so its unique doesn't 
+-- matter
+mkWildCoVar = mkCoVar (mkSysTvName (mkBuiltinUnique 1) (fsLit "co_wild"))
 \end{code}
 
 %************************************************************************
@@ -391,8 +383,9 @@ isLocalIdVar (LocalId {}) = True
 isLocalIdVar _            = False
 
 isCoVar :: Var -> Bool
-isCoVar (v@(TyVar {})) = isCoercionVar v
-isCoVar _              = False
+isCoVar (v@(TyVar {}))             = isCoercionVar v
+isCoVar (TcTyVar {varType = kind}) = isCoercionKind kind  -- used during solving
+isCoVar _                          = False
 
 -- | 'isLocalVar' returns @True@ for type variables as well as local 'Id's
 -- These are the variables that we need to pay attention to when finding free