Big tidy-up of deriving code

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

diff --git a/compiler/typecheck/TcHsType.lhs b/compiler/typecheck/TcHsType.lhs
index 7eac2a2..86870c9 100644 (file)
--- a/compiler/typecheck/TcHsType.lhs
+++ b/compiler/typecheck/TcHsType.lhs
@@ -6,7 +6,8 @@
 
 \begin{code}
 module TcHsType (
-       tcHsSigType, tcHsDeriv,
+       tcHsSigType, tcHsDeriv, 
+       tcHsInstHead, tcHsQuantifiedType,
        UserTypeCtxt(..), 
 
                -- Kind checking
@@ -143,6 +144,24 @@ tcHsSigType ctxt hs_ty
        ; checkValidType ctxt ty        
        ; returnM ty }
 
+tcHsInstHead :: LHsType Name -> TcM ([TyVar], ThetaType, Type)
+-- Typecheck an instance head.  We can't use 
+-- tcHsSigType, because it's not a valid user type.
+tcHsInstHead hs_ty
+  = do { kinded_ty <- kcHsSigType hs_ty
+       ; poly_ty   <- tcHsKindedType kinded_ty
+       ; return (tcSplitSigmaTy poly_ty) }
+
+tcHsQuantifiedType :: [LHsTyVarBndr Name] -> LHsType Name -> TcM ([TyVar], Type)
+-- Behave very like type-checking (HsForAllTy sig_tvs hs_ty),
+-- except that we want to keep the tvs separate
+tcHsQuantifiedType tv_names hs_ty
+  = kcHsTyVars tv_names $ \ tv_names' ->
+    do { kc_ty <- kcHsSigType hs_ty
+       ; tcTyVarBndrs tv_names' $ \ tvs ->
+    do { ty <- dsHsType kc_ty
+       ; return (tvs, ty) } }
+
 -- Used for the deriving(...) items
 tcHsDeriv :: LHsType Name -> TcM ([TyVar], Class, [Type])
 tcHsDeriv = addLocM (tc_hs_deriv [])
@@ -629,7 +648,7 @@ tcTyVarBndrs bndrs thing_inside
   where
     zonk (KindedTyVar name kind) = do { kind' <- zonkTcKindToKind kind
                                      ; return (mkTyVar name kind') }
-    zonk (UserTyVar name) = pprTrace "Un-kinded tyvar" (ppr name) $
+    zonk (UserTyVar name) = WARN( True, ptext SLIT("Un-kinded tyvar") <+> ppr name )
                            return (mkTyVar name liftedTypeKind)
 
 -----------------------------------
@@ -725,16 +744,10 @@ tcHsPatSigType ctxt hs_ty
                        | n <- nameSetToList (extractHsTyVars hs_ty),
                          not (in_scope n) ]
 
-       -- Behave very like type-checking (HsForAllTy sig_tvs hs_ty),
-       -- except that we want to keep the tvs separate
-       ; (kinded_tvs, kinded_ty) <- kcHsTyVars sig_tvs $ \ kinded_tvs -> do
-                                   { kinded_ty <- kcTypeType hs_ty
-                                   ; return (kinded_tvs, kinded_ty) }
-       ; tcTyVarBndrs kinded_tvs $ \ tyvars -> do
-       { sig_ty <- dsHsType kinded_ty
+       ; (tyvars, sig_ty) <- tcHsQuantifiedType sig_tvs hs_ty
        ; checkValidType ctxt sig_ty 
        ; return (tyvars, sig_ty)
-      } }
+      }
 
 tcPatSig :: UserTypeCtxt
         -> LHsType Name