\section[TcMonoType]{Typechecking user-specified @MonoTypes@}
\begin{code}
+{-# LANGUAGE RelaxedPolyRec #-}
+
module TcHsType (
tcHsSigType, tcHsDeriv,
tcHsInstHead, tcHsQuantifiedType,
-- Kind checking
kcHsTyVars, kcHsSigType, kcHsLiftedSigType,
- kcCheckHsType, kcHsContext, kcHsType,
+ kcLHsType, kcCheckLHsType, kcHsContext,
-- Typechecking kinded types
tcHsKindedContext, tcHsKindedType, tcHsBangType,
tc_hs_deriv tv_names (HsPredTy (HsClassP cls_name hs_tys))
= kcHsTyVars tv_names $ \ tv_names' ->
do { cls_kind <- kcClass cls_name
- ; (tys, _res_kind) <- kcApps cls_kind (ppr cls_name) hs_tys
+ ; (tys, _res_kind) <- kcApps cls_name cls_kind hs_tys
; tcTyVarBndrs tv_names' $ \ tyvars ->
do { arg_tys <- dsHsTypes tys
; cls <- tcLookupClass cls_name
\begin{code}
kcHsSigType, kcHsLiftedSigType :: LHsType Name -> TcM (LHsType Name)
-- Used for type signatures
-kcHsSigType ty = kcTypeType ty
-kcHsLiftedSigType ty = kcLiftedType ty
+kcHsSigType ty = addKcTypeCtxt ty $ kcTypeType ty
+kcHsLiftedSigType ty = addKcTypeCtxt ty $ kcLiftedType ty
tcHsKindedType :: LHsType Name -> TcM Type
-- Don't do kind checking, nor validity checking.
---------------------------
kcLiftedType :: LHsType Name -> TcM (LHsType Name)
-- The type ty must be a *lifted* *type*
-kcLiftedType ty = kcCheckHsType ty liftedTypeKind
+kcLiftedType ty = kc_check_lhs_type ty liftedTypeKind
---------------------------
kcTypeType :: LHsType Name -> TcM (LHsType Name)
-- The type ty must be a *type*, but it can be lifted or
-- unlifted or an unboxed tuple.
-kcTypeType ty = kcCheckHsType ty openTypeKind
+kcTypeType ty = kc_check_lhs_type ty openTypeKind
---------------------------
-kcCheckHsType :: LHsType Name -> TcKind -> TcM (LHsType Name)
+kcCheckLHsType :: LHsType Name -> TcKind -> TcM (LHsType Name)
+kcCheckLHsType ty kind = addKcTypeCtxt ty $ kc_check_lhs_type ty kind
+
+
+kc_check_lhs_type :: LHsType Name -> TcKind -> TcM (LHsType Name)
-- Check that the type has the specified kind
-- Be sure to use checkExpectedKind, rather than simply unifying
-- with OpenTypeKind, because it gives better error messages
-kcCheckHsType (L span ty) exp_kind
- = setSrcSpan span $
- do { (ty', act_kind) <- add_ctxt ty (kc_hs_type ty)
+kc_check_lhs_type (L span ty) exp_kind
+ = setSrcSpan span $
+ do { ty' <- kc_check_hs_type ty exp_kind
+ ; return (L span ty') }
+
+kc_check_lhs_types :: [(LHsType Name,TcKind)] -> TcM [LHsType Name]
+kc_check_lhs_types tys_w_kinds
+ = mapM kc_arg tys_w_kinds
+ where
+ kc_arg (arg, arg_kind) = kc_check_lhs_type arg arg_kind
+
+
+---------------------------
+kc_check_hs_type :: HsType Name -> TcKind -> TcM (HsType Name)
+
+-- First some special cases for better error messages
+-- when we know the expected kind
+kc_check_hs_type (HsParTy ty) exp_kind
+ = do { ty' <- kc_check_lhs_type ty exp_kind; return (HsParTy ty') }
+
+kc_check_hs_type ty@(HsAppTy ty1 ty2) exp_kind
+ = do { let (fun_ty, arg_tys) = splitHsAppTys ty1 ty2
+ ; (fun_ty', fun_kind) <- kc_lhs_type fun_ty
+ ; arg_tys' <- kcCheckApps fun_ty fun_kind arg_tys ty exp_kind
+ ; return (mkHsAppTys fun_ty' arg_tys') }
+
+kc_check_hs_type ty@(HsPredTy (HsClassP cls tys)) exp_kind
+ = do { cls_kind <- kcClass cls
+ ; tys' <- kcCheckApps cls cls_kind tys ty exp_kind
+ ; return (HsPredTy (HsClassP cls tys')) }
+
+-- This is the general case: infer the kind and compare
+kc_check_hs_type ty exp_kind
+ = do { (ty', act_kind) <- kc_hs_type ty
-- Add the context round the inner check only
-- because checkExpectedKind already mentions
-- 'ty' by name in any error message
; checkExpectedKind (strip ty) act_kind exp_kind
- ; return (L span ty') }
+ ; return ty' }
where
- -- Wrap a context around only if we want to show that contexts.
- add_ctxt (HsPredTy _) thing = thing
- -- Omit invisble ones and ones user's won't grok (HsPred p).
- add_ctxt (HsForAllTy _ _ (L _ []) _) thing = thing
- -- Omit wrapping if the theta-part is empty
- -- Reason: the recursive call to kcLiftedType, in the ForAllTy
- -- case of kc_hs_type, will do the wrapping instead
- -- and we don't want to duplicate
- add_ctxt other_ty thing = addErrCtxt (typeCtxt other_ty) thing
-
-- We infer the kind of the type, and then complain if it's
-- not right. But we don't want to complain about
-- (ty) or !(ty) or forall a. ty
strip (HsBangTy _ (L _ ty)) = strip ty
strip (HsForAllTy _ _ _ (L _ ty)) = strip ty
strip ty = ty
+
\end{code}
Here comes the main function
\begin{code}
-kcHsType :: LHsType Name -> TcM (LHsType Name, TcKind)
-kcHsType ty = wrapLocFstM kc_hs_type ty
--- kcHsType *returns* the kind of the type, rather than taking an expected
+kcLHsType :: LHsType Name -> TcM (LHsType Name, TcKind)
+-- Called from outside: set the context
+kcLHsType ty = addKcTypeCtxt ty (kc_lhs_type ty)
+
+kc_lhs_type :: LHsType Name -> TcM (LHsType Name, TcKind)
+kc_lhs_type (L span ty)
+ = setSrcSpan span $
+ do { (ty', kind) <- kc_hs_type ty
+ ; return (L span ty', kind) }
+
+-- kc_hs_type *returns* the kind of the type, rather than taking an expected
-- kind as argument as tcExpr does.
-- Reasons:
-- (a) the kind of (->) is
kc_hs_type :: HsType Name -> TcM (HsType Name, TcKind)
kc_hs_type (HsParTy ty) = do
- (ty', kind) <- kcHsType ty
+ (ty', kind) <- kc_lhs_type ty
return (HsParTy ty', kind)
kc_hs_type (HsTyVar name) = do
= return (HsNumTy n, liftedTypeKind)
kc_hs_type (HsKindSig ty k) = do
- ty' <- kcCheckHsType ty k
+ ty' <- kc_check_lhs_type ty k
return (HsKindSig ty' k, k)
kc_hs_type (HsTupleTy Boxed tys) = do
return (HsTupleTy Unboxed tys', ubxTupleKind)
kc_hs_type (HsFunTy ty1 ty2) = do
- ty1' <- kcCheckHsType ty1 argTypeKind
+ ty1' <- kc_check_lhs_type ty1 argTypeKind
ty2' <- kcTypeType ty2
return (HsFunTy ty1' ty2', liftedTypeKind)
kc_hs_type (HsOpTy ty1 op ty2) = do
op_kind <- addLocM kcTyVar op
- ([ty1',ty2'], res_kind) <- kcApps op_kind (ppr op) [ty1,ty2]
+ ([ty1',ty2'], res_kind) <- kcApps op op_kind [ty1,ty2]
return (HsOpTy ty1' op ty2', res_kind)
kc_hs_type (HsAppTy ty1 ty2) = do
- (fun_ty', fun_kind) <- kcHsType fun_ty
- ((arg_ty':arg_tys'), res_kind) <- kcApps fun_kind (ppr fun_ty) arg_tys
- return (foldl mk_app (HsAppTy fun_ty' arg_ty') arg_tys', res_kind)
+ (fun_ty', fun_kind) <- kc_lhs_type fun_ty
+ (arg_tys', res_kind) <- kcApps fun_ty fun_kind arg_tys
+ return (mkHsAppTys fun_ty' arg_tys', res_kind)
where
- (fun_ty, arg_tys) = split ty1 [ty2]
- split (L _ (HsAppTy f a)) as = split f (a:as)
- split f as = (f,as)
- mk_app fun arg = HsAppTy (noLoc fun) arg -- Add noLocs for inner nodes of
- -- the application; they are
- -- never used
+ (fun_ty, arg_tys) = splitHsAppTys ty1 ty2
kc_hs_type (HsPredTy (HsEqualP _ _))
= wrongEqualityErr
; return (HsForAllTy exp tv_names' ctxt' ty', liftedTypeKind) }
kc_hs_type (HsBangTy b ty) = do
- (ty', kind) <- kcHsType ty
+ (ty', kind) <- kc_lhs_type ty
return (HsBangTy b ty', kind)
kc_hs_type ty@(HsSpliceTy _)
= kc_hs_type (unLoc ty)
---------------------------
-kcApps :: TcKind -- Function kind
- -> SDoc -- Function
+kcApps :: Outputable a
+ => a
+ -> TcKind -- Function kind
-> [LHsType Name] -- Arg types
-> TcM ([LHsType Name], TcKind) -- Kind-checked args
-kcApps fun_kind ppr_fun args = do
- (arg_kinds, res_kind) <- split_fk fun_kind (length args)
- args' <- zipWithM kc_arg args arg_kinds
- return (args', res_kind)
+kcApps the_fun fun_kind args
+ = do { (args_w_kinds, res_kind) <- splitFunKind the_fun fun_kind args
+ ; args' <- kc_check_lhs_types args_w_kinds
+ ; return (args', res_kind) }
+
+kcCheckApps :: Outputable a => a -> TcKind -> [LHsType Name]
+ -> HsType Name -- The type being checked (for err messages only)
+ -> TcKind -- Expected kind
+ -> TcM [LHsType Name]
+kcCheckApps the_fun fun_kind args ty exp_kind
+ = do { (args_w_kinds, res_kind) <- splitFunKind the_fun fun_kind args
+ ; checkExpectedKind ty res_kind exp_kind
+ -- Check the result kind *before* checking argument kinds
+ -- This improves error message; Trac #2994
+ ; kc_check_lhs_types args_w_kinds }
+
+splitHsAppTys :: LHsType Name -> LHsType Name -> (LHsType Name, [LHsType Name])
+splitHsAppTys fun_ty arg_ty = split fun_ty [arg_ty]
where
- split_fk fk 0 = return ([], fk)
- split_fk fk n = do mb_fk <- unifyFunKind fk
- case mb_fk of
- Nothing -> failWithTc too_many_args
- Just (ak,fk') -> do (aks, rk) <- split_fk fk' (n-1)
- return (ak:aks, rk)
+ split (L _ (HsAppTy f a)) as = split f (a:as)
+ split f as = (f,as)
- kc_arg arg arg_kind = kcCheckHsType arg arg_kind
+mkHsAppTys :: LHsType Name -> [LHsType Name] -> HsType Name
+mkHsAppTys fun_ty [] = pprPanic "mkHsAppTys" (ppr fun_ty)
+mkHsAppTys fun_ty (arg_ty:arg_tys)
+ = foldl mk_app (HsAppTy fun_ty arg_ty) arg_tys
+ where
+ mk_app fun arg = HsAppTy (noLoc fun) arg -- Add noLocs for inner nodes of
+ -- the application; they are
+ -- never used
- too_many_args = ptext (sLit "Kind error:") <+> quotes ppr_fun <+>
+---------------------------
+splitFunKind :: Outputable a => a -> TcKind -> [b] -> TcM ([(b,TcKind)], TcKind)
+splitFunKind _ fk [] = return ([], fk)
+splitFunKind the_fun fk (arg:args)
+ = do { mb_fk <- unifyFunKind fk
+ ; case mb_fk of
+ Nothing -> failWithTc too_many_args
+ Just (ak,fk') -> do { (aks, rk) <- splitFunKind the_fun fk' args
+ ; return ((arg,ak):aks, rk) } }
+ where
+ too_many_args = quotes (ppr the_fun) <+>
ptext (sLit "is applied to too many type arguments")
---------------------------
-- Does *not* check for a saturated
-- application (reason: used from TcDeriv)
kc_pred (HsIParam name ty)
- = do { (ty', kind) <- kcHsType ty
+ = do { (ty', kind) <- kc_lhs_type ty
; return (HsIParam name ty', kind)
}
kc_pred (HsClassP cls tys)
= do { kind <- kcClass cls
- ; (tys', res_kind) <- kcApps kind (ppr cls) tys
+ ; (tys', res_kind) <- kcApps cls kind tys
; return (HsClassP cls tys', res_kind)
}
kc_pred (HsEqualP ty1 ty2)
- = do { (ty1', kind1) <- kcHsType ty1
+ = do { (ty1', kind1) <- kc_lhs_type ty1
-- ; checkExpectedKind ty1 kind1 liftedTypeKind
- ; (ty2', kind2) <- kcHsType ty2
+ ; (ty2', kind2) <- kc_lhs_type ty2
-- ; checkExpectedKind ty2 kind2 liftedTypeKind
; checkExpectedKind ty2 kind2 kind1
; return (HsEqualP ty1' ty2', liftedTypeKind)
= hang (ptext (sLit "Malformed constructor result type:"))
2 (ppr ty)
+addKcTypeCtxt :: LHsType Name -> TcM a -> TcM a
+ -- Wrap a context around only if we want to show that contexts.
+addKcTypeCtxt (L _ (HsPredTy _)) thing = thing
+ -- Omit invisble ones and ones user's won't grok (HsPred p).
+addKcTypeCtxt (L _ other_ty) thing = addErrCtxt (typeCtxt other_ty) thing
+
typeCtxt :: HsType Name -> SDoc
typeCtxt ty = ptext (sLit "In the type") <+> quotes (ppr ty)
\end{code}
projects / ghc-hetmet.git / blobdiff