\section[TcTyDecls]{Typecheck type declarations}
\begin{code}
-module TcTyDecls (
- tcTyDecl1,
- kcConDetails,
- mkImplicitDataBinds, mkNewTyConRep
- ) where
+module TcTyDecls ( tcTyDecl, checkValidTyCon, kcConDetails ) where
#include "HsVersions.h"
-import HsSyn ( MonoBinds(..),
- TyClDecl(..), ConDecl(..), ConDetails(..), BangType(..),
- getBangType
+import HsSyn ( TyClDecl(..), ConDecl(..), ConDetails(..),
+ getBangType, getBangStrictness, conDetailsTys
)
import RnHsSyn ( RenamedTyClDecl, RenamedConDecl, RenamedContext )
-import TcHsSyn ( TcMonoBinds, idsToMonoBinds )
import BasicTypes ( NewOrData(..) )
-import TcMonoType ( tcHsType, tcHsSigType, tcHsBoxedSigType, tcHsTyVars, tcClassContext,
- kcHsContext, kcHsSigType
+import TcMonoType ( tcHsTyVars, tcHsTheta, tcHsType,
+ kcHsContext, kcHsSigType, kcHsLiftedSigType
)
import TcEnv ( tcExtendTyVarEnv,
- tcLookupTyCon, tcLookupClass, tcLookupGlobalId,
- TyThingDetails(..)
+ tcLookupTyCon, tcLookupRecId,
+ TyThingDetails(..), RecTcEnv
)
+import TcType ( tcEqType, tyVarsOfTypes, tyVarsOfPred, ThetaType )
+import TcMType ( checkValidType, UserTypeCtxt(..), checkValidTheta, SourceTyCtxt(..) )
import TcMonad
-import Class ( ClassContext )
-import DataCon ( DataCon, mkDataCon,
- dataConFieldLabels, dataConId, dataConWrapId,
- markedStrict, notMarkedStrict, markedUnboxed, dataConRepType
- )
+import DataCon ( DataCon, mkDataCon, dataConFieldLabels, dataConWrapId, dataConName )
import MkId ( mkDataConId, mkDataConWrapId, mkRecordSelId )
import FieldLabel
-import Var ( Id, TyVar )
-import Name ( Name, isLocallyDefined, NamedThing(..) )
+import Var ( TyVar, idType )
+import Name ( Name, NamedThing(..) )
import Outputable
-import TyCon ( TyCon, isSynTyCon, isNewTyCon,
- tyConDataConsIfAvailable, tyConTyVars, tyConGenIds
- )
-import Type ( tyVarsOfTypes, splitFunTy, applyTys,
- mkTyConApp, mkTyVarTys, mkForAllTys,
- splitAlgTyConApp_maybe, Type
- )
-import TysWiredIn ( unitTy )
+import TyCon ( TyCon, tyConName, tyConTheta, getSynTyConDefn, tyConTyVars, tyConDataCons, isSynTyCon )
import VarSet ( intersectVarSet, isEmptyVarSet )
import PrelNames ( unpackCStringName, unpackCStringUtf8Name )
import ListSetOps ( equivClasses )
+import List ( nubBy )
\end{code}
%************************************************************************
%************************************************************************
\begin{code}
-tcTyDecl1 :: RenamedTyClDecl -> TcM (Name, TyThingDetails)
-tcTyDecl1 (TySynonym tycon_name tyvar_names rhs src_loc)
+tcTyDecl :: RecTcEnv -> RenamedTyClDecl -> TcM (Name, TyThingDetails)
+tcTyDecl unf_env (TySynonym {tcdName = tycon_name, tcdSynRhs = rhs})
= tcLookupTyCon tycon_name `thenNF_Tc` \ tycon ->
tcExtendTyVarEnv (tyConTyVars tycon) $
tcHsType rhs `thenTc` \ rhs_ty ->
- -- Note tcHsType not tcHsSigType; we allow type synonyms
- -- that aren't types; e.g. type List = []
- --
- -- If the RHS mentions tyvars that aren't in scope, we'll
- -- quantify over them:
- -- e.g. type T = a->a
- -- will become type T = forall a. a->a
- --
- -- With gla-exts that's right, but for H98 we should complain.
- -- We can now do that here without falling into
- -- a black hole, we still do it in rnDecl (TySynonym case)
-
returnTc (tycon_name, SynTyDetails rhs_ty)
-tcTyDecl1 (TyData new_or_data context tycon_name _ con_decls _ derivings src_loc name1 name2)
+tcTyDecl unf_env (TyData {tcdND = new_or_data, tcdCtxt = context,
+ tcdName = tycon_name, tcdCons = con_decls})
= tcLookupTyCon tycon_name `thenNF_Tc` \ tycon ->
let
tyvars = tyConTyVars tycon
in
tcExtendTyVarEnv tyvars $
-
- -- Typecheck the pieces
- tcClassContext context `thenTc` \ ctxt ->
- tc_derivs derivings `thenTc` \ derived_classes ->
+ tcHsTheta context `thenTc` \ ctxt ->
mapTc (tcConDecl new_or_data tycon tyvars ctxt) con_decls `thenTc` \ data_cons ->
+ let
+ sel_ids = mkRecordSelectors unf_env tycon data_cons
+ in
+ returnTc (tycon_name, DataTyDetails ctxt data_cons sel_ids)
+
+tcTyDecl unf_env (ForeignType {tcdName = tycon_name})
+ = returnTc (tycon_name, ForeignTyDetails)
- returnTc (tycon_name, DataTyDetails ctxt data_cons derived_classes)
+
+mkRecordSelectors unf_env tycon data_cons
+ = -- We'll check later that fields with the same name
+ -- from different constructors have the same type.
+ [ mkRecordSelId tycon field unpack_id unpackUtf8_id
+ | field <- nubBy eq_name fields ]
where
- tc_derivs Nothing = returnTc []
- tc_derivs (Just ds) = mapTc tcLookupClass ds
+ fields = [ field | con <- data_cons, field <- dataConFieldLabels con ]
+ eq_name field1 field2 = fieldLabelName field1 == fieldLabelName field2
+
+ unpack_id = tcLookupRecId unf_env unpackCStringName
+ unpackUtf8_id = tcLookupRecId unf_env unpackCStringUtf8Name
\end{code}
+
+%************************************************************************
+%* *
+\subsection{Validity check}
+%* *
+%************************************************************************
+
+checkValidTyCon is called once the mutually-recursive knot has been
+tied, so we can look at things freely.
+
\begin{code}
-mkNewTyConRep :: TyCon -> Type
--- Find the representation type for this newtype TyCon
--- The trick is to to deal correctly with recursive newtypes
--- such as newtype T = MkT T
+checkValidTyCon :: TyCon -> TcM ()
+checkValidTyCon tc
+ | isSynTyCon tc = checkValidType (TySynCtxt name) syn_rhs
+ | otherwise
+ = -- Check the context on the data decl
+ checkValidTheta (DataTyCtxt name) (tyConTheta tc) `thenTc_`
+
+ -- Check arg types of data constructors
+ mapTc_ check_data_con data_cons `thenTc_`
+
+ -- Check that fields with the same name share a type
+ mapTc_ check_fields groups
-mkNewTyConRep tc
- = mkForAllTys tvs (loop [] (mkTyConApp tc (mkTyVarTys tvs)))
where
- tvs = tyConTyVars tc
- loop tcs ty = case splitAlgTyConApp_maybe ty of {
- Nothing -> ty ;
- Just (tc, tys, data_cons) | not (isNewTyCon tc) -> ty
- | tc `elem` tcs -> unitTy
- | otherwise ->
-
- case splitFunTy (applyTys (dataConRepType (head data_cons)) tys) of
- (rep_ty, _) -> loop (tc:tcs) rep_ty
- }
+ name = tyConName tc
+ (_, syn_rhs) = getSynTyConDefn tc
+ data_cons = tyConDataCons tc
+
+ fields = [field | con <- data_cons, field <- dataConFieldLabels con]
+ groups = equivClasses cmp_name fields
+ cmp_name field1 field2 = fieldLabelName field1 `compare` fieldLabelName field2
+
+ check_data_con con = checkValidType (ConArgCtxt (dataConName con))
+ (idType (dataConWrapId con))
+ -- This checks the argument types and
+ -- the existential context (if any)
+
+ check_fields fields@(first_field_label : other_fields)
+ -- These fields all have the same name, but are from
+ -- different constructors in the data type
+ = -- Check that all the fields in the group have the same type
+ -- NB: this check assumes that all the constructors of a given
+ -- data type use the same type variables
+ checkTc (all (tcEqType field_ty) other_tys) (fieldTypeMisMatch field_name)
+ where
+ field_ty = fieldLabelType first_field_label
+ field_name = fieldLabelName first_field_label
+ other_tys = map fieldLabelType other_fields
\end{code}
+
%************************************************************************
%* *
\subsection{Kind and type check constructors}
%************************************************************************
\begin{code}
-kcConDetails :: RenamedContext -> ConDetails Name -> TcM ()
-kcConDetails ex_ctxt details
+kcConDetails :: NewOrData -> RenamedContext -> ConDetails Name -> TcM ()
+kcConDetails new_or_data ex_ctxt details
= kcHsContext ex_ctxt `thenTc_`
- kc_con_details details
+ mapTc_ kc_sig_type (conDetailsTys details)
where
- kc_con_details (VanillaCon btys) = mapTc_ kc_bty btys
- kc_con_details (InfixCon bty1 bty2) = mapTc_ kc_bty [bty1,bty2]
- kc_con_details (RecCon flds) = mapTc_ kc_field flds
-
- kc_field (_, bty) = kc_bty bty
-
- kc_bty bty = kcHsSigType (getBangType bty)
+ kc_sig_type = case new_or_data of
+ DataType -> kcHsSigType
+ NewType -> kcHsLiftedSigType
+ -- Can't allow an unlifted type here, because we're effectively
+ -- going to remove the constructor while coercing it to a lifted type.
-tcConDecl :: NewOrData -> TyCon -> [TyVar] -> ClassContext -> RenamedConDecl -> TcM DataCon
+tcConDecl :: NewOrData -> TyCon -> [TyVar] -> ThetaType -> RenamedConDecl -> TcM DataCon
tcConDecl new_or_data tycon tyvars ctxt (ConDecl name wkr_name ex_tvs ex_ctxt details src_loc)
- = tcAddSrcLoc src_loc $
- tcHsTyVars ex_tvs (kcConDetails ex_ctxt details) $ \ ex_tyvars ->
- tcClassContext ex_ctxt `thenTc` \ ex_theta ->
+ = tcAddSrcLoc src_loc $
+ tcHsTyVars ex_tvs (kcConDetails new_or_data ex_ctxt details) $ \ ex_tyvars ->
+ tcHsTheta ex_ctxt `thenTc` \ ex_theta ->
case details of
VanillaCon btys -> tc_datacon ex_tyvars ex_theta btys
InfixCon bty1 bty2 -> tc_datacon ex_tyvars ex_theta [bty1,bty2]
RecCon fields -> tc_rec_con ex_tyvars ex_theta fields
where
- tc_sig_type = case new_or_data of
- DataType -> tcHsSigType
- NewType -> tcHsBoxedSigType
- -- Can't allow an unboxed type here, because we're effectively
- -- going to remove the constructor while coercing it to a boxed type.
-
tc_datacon ex_tyvars ex_theta btys
- = let
- arg_stricts = map getBangStrictness btys
- tys = map getBangType btys
- in
- mapTc tc_sig_type tys `thenTc` \ arg_tys ->
- mk_data_con ex_tyvars ex_theta arg_stricts arg_tys []
+ = mapTc tcHsType (map getBangType btys) `thenTc` \ arg_tys ->
+ mk_data_con ex_tyvars ex_theta (map getBangStrictness btys) arg_tys []
tc_rec_con ex_tyvars ex_theta fields
= checkTc (null ex_tyvars) (exRecConErr name) `thenTc_`
let
field_labels = concat field_labels_s
arg_stricts = [str | (ns, bty) <- fields,
- let str = getBangStrictness bty,
- n <- ns -- One for each. E.g x,y,z :: !Int
+ let str = getBangStrictness bty,
+ n <- ns -- One for each. E.g x,y,z :: !Int
]
in
mk_data_con ex_tyvars ex_theta arg_stricts
(map fieldLabelType field_labels) field_labels
tc_field ((field_label_names, bty), tag)
- = tc_sig_type (getBangType bty) `thenTc` \ field_ty ->
+ = tcHsType (getBangType bty) `thenTc` \ field_ty ->
returnTc [mkFieldLabel (getName name) tycon field_ty tag | name <- field_label_names]
mk_data_con ex_tyvars ex_theta arg_stricts arg_tys fields
= filter in_arg_tys ctxt
where
arg_tyvars = tyVarsOfTypes arg_tys
- in_arg_tys (clas,tys) = not $ isEmptyVarSet $
- tyVarsOfTypes tys `intersectVarSet` arg_tyvars
-
-getBangStrictness (Banged _) = markedStrict
-getBangStrictness (Unbanged _) = notMarkedStrict
-getBangStrictness (Unpacked _) = markedUnboxed
+ in_arg_tys pred = not $ isEmptyVarSet $
+ tyVarsOfPred pred `intersectVarSet` arg_tyvars
\end{code}
-
%************************************************************************
%* *
-\subsection{Generating constructor/selector bindings for data declarations}
+\subsection{Errors and contexts}
%* *
%************************************************************************
-\begin{code}
-mkImplicitDataBinds :: [TyCon] -> TcM ([Id], TcMonoBinds)
-mkImplicitDataBinds [] = returnTc ([], EmptyMonoBinds)
-mkImplicitDataBinds (tycon : tycons)
- | isSynTyCon tycon = mkImplicitDataBinds tycons
- | otherwise = mkImplicitDataBinds_one tycon `thenTc` \ (ids1, b1) ->
- mkImplicitDataBinds tycons `thenTc` \ (ids2, b2) ->
- returnTc (ids1++ids2, b1 `AndMonoBinds` b2)
-
-mkImplicitDataBinds_one tycon
- = mapTc (mkRecordSelector tycon) groups `thenTc` \ sel_ids ->
- let
- unf_ids = sel_ids ++ data_con_wrapper_ids ++ gen_ids
- all_ids = map dataConId data_cons ++ unf_ids
-
- -- For the locally-defined things
- -- we need to turn the unfoldings inside the selector Ids into bindings,
- -- and build bindigns for the constructor wrappers
- binds | isLocallyDefined tycon = idsToMonoBinds unf_ids
- | otherwise = EmptyMonoBinds
- in
- returnTc (all_ids, binds)
- where
- data_cons = tyConDataConsIfAvailable tycon
- -- Abstract types mean we don't bring the
- -- data cons into scope, which should be fine
- gen_ids = tyConGenIds tycon
- data_con_wrapper_ids = map dataConWrapId data_cons
-
- fields = [ (con, field) | con <- data_cons,
- field <- dataConFieldLabels con
- ]
-
- -- groups is list of fields that share a common name
- groups = equivClasses cmp_name fields
- cmp_name (_, field1) (_, field2)
- = fieldLabelName field1 `compare` fieldLabelName field2
-\end{code}
-
-\begin{code}
-mkRecordSelector tycon fields@((first_con, first_field_label) : other_fields)
- -- These fields all have the same name, but are from
- -- different constructors in the data type
- -- Check that all the fields in the group have the same type
- -- This check assumes that all the constructors of a given
- -- data type use the same type variables
- = checkTc (all (== field_ty) other_tys)
- (fieldTypeMisMatch field_name) `thenTc_`
- tcLookupGlobalId unpackCStringName `thenTc` \ unpack_id ->
- tcLookupGlobalId unpackCStringUtf8Name `thenTc` \ unpackUtf8_id ->
- returnTc (mkRecordSelId tycon first_field_label unpack_id unpackUtf8_id)
- where
- field_ty = fieldLabelType first_field_label
- field_name = fieldLabelName first_field_label
- other_tys = [fieldLabelType fl | (_, fl) <- other_fields]
-\end{code}
-
-Errors and contexts
-~~~~~~~~~~~~~~~~~~~
\begin{code}
fieldTypeMisMatch field_name
- = sep [ptext SLIT("Declared types differ for field"), quotes (ppr field_name)]
+ = sep [ptext SLIT("Different constructors give different types for field"), quotes (ppr field_name)]
exRecConErr name
= ptext SLIT("Can't combine named fields with locally-quantified type variables")
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