#include "HsVersions.h"
import HsSyn ( HsType(..), LHsType, HsTyVarBndr(..), LHsTyVarBndr,
- LHsContext, HsPred(..), LHsPred, HsExplicitForAll(..) )
+ LHsContext, HsPred(..), LHsPred )
import RnHsSyn ( extractHsTyVars )
import TcRnMonad
import TcEnv ( tcExtendTyVarEnv, tcExtendKindEnvTvs,
substTyWith, mkTyVarTys, tcEqType,
tcIsTyVarTy, mkFunTy, mkSigmaTy, mkPredTy,
mkTyConApp, mkAppTys, typeKind )
-import Kind ( Kind, isLiftedTypeKind, liftedTypeKind, ubxTupleKind,
+import {- Kind parts of -} Type ( Kind, isLiftedTypeKind, liftedTypeKind, ubxTupleKind,
openTypeKind, argTypeKind, splitKindFunTys )
import Var ( TyVar, mkTyVar, tyVarName )
import TyCon ( TyCon, tyConKind )
kcHsLiftedSigType ty = kcLiftedType ty
tcHsKindedType :: LHsType Name -> TcM Type
- -- Don't do kind checking, nor validity checking,
- -- but do hoist for-alls to the top
+ -- Don't do kind checking, nor validity checking.
-- This is used in type and class decls, where kinding is
-- done in advance, and validity checking is done later
-- [Validity checking done later because of knot-tying issues.]
-- because checkExpectedKind already mentions
-- 'ty' by name in any error message
- ; checkExpectedKind ty act_kind exp_kind
+ ; checkExpectedKind (strip ty) act_kind exp_kind
; return (L span ty') }
where
- -- Wrap a context around only if we want to
- -- show that contexts. Omit invisble ones
- -- and ones user's won't grok (HsPred p).
- add_ctxt (HsPredTy p) thing = thing
- add_ctxt (HsForAllTy Implicit tvs (L _ []) ty) thing = thing
- add_ctxt other_ty thing = addErrCtxt (typeCtxt ty) thing
+ -- Wrap a context around only if we want to show that contexts.
+ add_ctxt (HsPredTy p) 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
+ -- when the real difficulty is with the 'ty' part.
+ strip (HsParTy (L _ ty)) = strip ty
+ strip (HsBangTy _ (L _ ty)) = strip ty
+ strip (HsForAllTy _ _ _ (L _ ty)) = strip ty
+ strip ty = ty
\end{code}
Here comes the main function
kc_hs_type (HsForAllTy exp tv_names context ty)
= kcHsTyVars tv_names $ \ tv_names' ->
- kcHsContext context `thenM` \ ctxt' ->
- kcLiftedType ty `thenM` \ ty' ->
- -- The body of a forall is usually a type, but in principle
- -- there's no reason to prohibit *unlifted* types.
- -- In fact, GHC can itself construct a function with an
- -- unboxed tuple inside a for-all (via CPR analyis; see
- -- typecheck/should_compile/tc170)
- --
- -- Still, that's only for internal interfaces, which aren't
- -- kind-checked, so we only allow liftedTypeKind here
- returnM (HsForAllTy exp tv_names' ctxt' ty', liftedTypeKind)
+ do { ctxt' <- kcHsContext context
+ ; ty' <- kcLiftedType ty
+ -- The body of a forall is usually a type, but in principle
+ -- there's no reason to prohibit *unlifted* types.
+ -- In fact, GHC can itself construct a function with an
+ -- unboxed tuple inside a for-all (via CPR analyis; see
+ -- typecheck/should_compile/tc170)
+ --
+ -- Still, that's only for internal interfaces, which aren't
+ -- kind-checked, so we only allow liftedTypeKind here
+
+ ; return (HsForAllTy exp tv_names' ctxt' ty', liftedTypeKind) }
kc_hs_type (HsBangTy b ty)
= do { (ty', kind) <- kcHsType ty
dsHsType ty `thenM` \ tau ->
returnM (mkSigmaTy tyvars theta tau)
+ds_type (HsSpliceTy {}) = panic "ds_type: HsSpliceTy"
+
dsHsTypes arg_tys = mappM dsHsType arg_tys
\end{code}
\begin{code}
tcLHsConResTy :: LHsType Name -> TcM (TyCon, [TcType])
-tcLHsConResTy ty@(L span _)
- = setSrcSpan span $
- addErrCtxt (gadtResCtxt ty) $
- tc_con_res ty []
-
-tc_con_res (L _ (HsAppTy fun res_ty)) res_tys
- = do { res_ty' <- dsHsType res_ty
- ; tc_con_res fun (res_ty' : res_tys) }
-
-tc_con_res ty@(L _ (HsTyVar name)) res_tys
- = do { thing <- tcLookup name
- ; case thing of
- AGlobal (ATyCon tc) -> return (tc, res_tys)
- other -> failWithTc (badGadtDecl ty)
- }
-
-tc_con_res ty _ = failWithTc (badGadtDecl ty)
+tcLHsConResTy res_ty
+ = addErrCtxt (gadtResCtxt res_ty) $
+ case get_largs res_ty [] of
+ (HsTyVar tc_name, args)
+ -> do { args' <- mapM dsHsType args
+ ; thing <- tcLookup tc_name
+ ; case thing of
+ AGlobal (ATyCon tc) -> return (tc, args')
+ other -> failWithTc (badGadtDecl res_ty) }
+ other -> failWithTc (badGadtDecl res_ty)
+ where
+ -- We can't call dsHsType on res_ty, and then do tcSplitTyConApp_maybe
+ -- because that causes a black hole, and for good reason. Building
+ -- the type means expanding type synonyms, and we can't do that
+ -- inside the "knot". So we have to work by steam.
+ get_largs (L _ ty) args = get_args ty args
+ get_args (HsAppTy fun arg) args = get_largs fun (arg:args)
+ get_args (HsParTy ty) args = get_largs ty args
+ get_args (HsOpTy ty1 (L span tc) ty2) args = (HsTyVar tc, ty1:ty2:args)
+ get_args ty args = (ty, args)
gadtResCtxt ty
= hang (ptext SLIT("In the result type of a data constructor:"))
-----------------------------------
tcDataKindSig :: Maybe Kind -> TcM [TyVar]
--- GADT decls can have a (perhpas partial) kind signature
+-- GADT decls can have a (perhaps partial) kind signature
-- e.g. data T :: * -> * -> * where ...
-- This function makes up suitable (kinded) type variables for
--- the argument kinds, and checks that the result kind is indeed *
+-- the argument kinds, and checks that the result kind is indeed *.
+-- We use it also to make up argument type variables for for data instances.
tcDataKindSig Nothing = return []
tcDataKindSig (Just kind)
= do { checkTc (isLiftedTypeKind res_kind) (badKindSig kind)
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