%
-% (c) The AQUA Project, Glasgow University, 1996
+% (c) The AQUA Project, Glasgow University, 1996-1998
%
\section[TcTyDecls]{Typecheck type declarations}
\begin{code}
-#include "HsVersions.h"
-
module TcTyDecls (
- tcTyDecl,
- tcConDecl,
- tcRecordSelectors
+ tcTyDecl1, kcConDetails, mkNewTyConRep
) where
-import Ubiq{-uitous-}
+#include "HsVersions.h"
-import HsSyn ( TyDecl(..), ConDecl(..), BangType(..), HsExpr(..),
- Match(..), GRHSsAndBinds(..), GRHS(..), OutPat(..),
- HsBinds(..), HsLit, Stmt, Qual, ArithSeqInfo, PolyType,
- Bind(..), MonoBinds(..), Sig,
- MonoType )
-import RnHsSyn ( RenamedTyDecl(..), RenamedConDecl(..),
- RnName{-instance Outputable-}
+import HsSyn ( TyClDecl(..), ConDecl(..), ConDetails(..),
+ getBangType, getBangStrictness, conDetailsTys
)
-import TcHsSyn ( TcHsBinds(..), TcIdOcc(..), mkHsTyLam )
+import RnHsSyn ( RenamedTyClDecl, RenamedConDecl, RenamedContext )
+import BasicTypes ( NewOrData(..), RecFlag, isRec )
-import TcMonoType ( tcMonoTypeKind, tcMonoType, tcContext )
-import TcType ( tcInstTyVars, tcInstType )
-import TcEnv ( tcLookupTyCon, tcLookupTyVar, tcLookupClass,
- newLocalId
+import TcMonoType ( tcHsRecType, tcHsTyVars, tcRecTheta,
+ kcHsContext, kcHsSigType, kcHsLiftedSigType
+ )
+import TcEnv ( tcExtendTyVarEnv,
+ tcLookupTyCon, tcLookupRecId,
+ TyThingDetails(..), RecTcEnv
)
import TcMonad
-import TcKind ( TcKind, unifyKind, mkTcArrowKind, mkTcTypeKind )
-import Id ( mkDataCon, dataConSig, mkRecordSelId,
- dataConFieldLabels, StrictnessMark(..)
- )
+import DataCon ( DataCon, mkDataCon, dataConFieldLabels, dataConRepType )
+import MkId ( mkDataConId, mkDataConWrapId, mkRecordSelId )
import FieldLabel
-import Kind ( Kind, mkArrowKind, mkBoxedTypeKind )
-import SpecEnv ( SpecEnv(..), nullSpecEnv )
-import Name ( Name{-instance Ord3-} )
-import Pretty
-import TyCon ( TyCon, NewOrData(..), mkSynTyCon, mkDataTyCon, tyConDataCons )
-import Type ( getTypeKind, getTyVar, tyVarsOfTypes, eqTy, applyTyCon,
- mkForAllTys, mkFunTy )
-import TyVar ( getTyVarKind, elementOfTyVarSet )
-import UniqSet ( emptyUniqSet, mkUniqSet, uniqSetToList, unionManyUniqSets, UniqSet(..) )
-import Util ( panic, equivClasses )
-\end{code}
-
-\begin{code}
-tcTyDecl :: RenamedTyDecl -> TcM s TyCon
-\end{code}
-
-Type synonym decls
-~~~~~~~~~~~~~~~~~~
-
-\begin{code}
-tcTyDecl (TySynonym tycon_name tyvar_names rhs src_loc)
- = tcAddSrcLoc src_loc $
- tcAddErrCtxt (tySynCtxt tycon_name) $
-
- -- Look up the pieces
- tcLookupTyCon tycon_name `thenNF_Tc` \ (tycon_kind, _, rec_tycon) ->
- mapAndUnzipNF_Tc tcLookupTyVar tyvar_names `thenNF_Tc` \ (tyvar_kinds, rec_tyvars) ->
-
- -- Look at the rhs
- tcMonoTypeKind rhs `thenTc` \ (rhs_kind, rhs_ty) ->
-
- -- Unify tycon kind with (k1->...->kn->rhs)
- unifyKind tycon_kind
- (foldr mkTcArrowKind rhs_kind tyvar_kinds)
- `thenTc_`
- let
- -- Getting the TyCon's kind is a bit of a nuisance. We can't use the tycon_kind,
- -- because that's a TcKind and may not yet be fully unified with other kinds.
- -- We could have augmented the tycon environment with a knot-tied kind,
- -- but the simplest thing to do seems to be to get the Kind by (lazily)
- -- looking at the tyvars and rhs_ty.
- result_kind, final_tycon_kind :: Kind -- NB not TcKind!
- result_kind = getTypeKind rhs_ty
- final_tycon_kind = foldr (mkArrowKind . getTyVarKind) result_kind rec_tyvars
-
- -- Construct the tycon
- tycon = mkSynTyCon (getName tycon_name)
- final_tycon_kind
- (length tyvar_names)
- rec_tyvars
- rhs_ty
- in
- returnTc tycon
+import Var ( TyVar )
+import Name ( Name, NamedThing(..) )
+import Outputable
+import TyCon ( TyCon, isNewTyCon, tyConTyVars )
+import Type ( tyVarsOfTypes, tyVarsOfPred, splitFunTy, applyTys,
+ mkTyConApp, mkTyVarTys, mkForAllTys,
+ splitAlgTyConApp_maybe, Type, ThetaType
+ )
+import TysWiredIn ( unitTy )
+import VarSet ( intersectVarSet, isEmptyVarSet )
+import PrelNames ( unpackCStringName, unpackCStringUtf8Name )
+import ListSetOps ( equivClasses )
\end{code}
-Algebraic data and newtype decls
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+%************************************************************************
+%* *
+\subsection{Type checking}
+%* *
+%************************************************************************
\begin{code}
-tcTyDecl (TyData context tycon_name tyvar_names con_decls derivings pragmas src_loc)
- = tcTyDataOrNew DataType context tycon_name tyvar_names con_decls derivings pragmas src_loc
-
-tcTyDecl (TyNew context tycon_name tyvar_names con_decl derivings pragmas src_loc)
- = tcTyDataOrNew NewType context tycon_name tyvar_names con_decl derivings pragmas src_loc
-
-
-tcTyDataOrNew data_or_new context tycon_name tyvar_names con_decls derivings pragmas src_loc
- = tcAddSrcLoc src_loc $
- tcAddErrCtxt (tyDataCtxt tycon_name) $
-
- -- Lookup the pieces
- tcLookupTyCon tycon_name `thenNF_Tc` \ (tycon_kind, _, rec_tycon) ->
- mapAndUnzipNF_Tc tcLookupTyVar tyvar_names `thenNF_Tc` \ (tyvar_kinds, rec_tyvars) ->
- tc_derivs derivings `thenNF_Tc` \ derived_classes ->
-
- -- Typecheck the context
- tcContext context `thenTc` \ ctxt ->
-
- -- Unify tycon kind with (k1->...->kn->Type)
- unifyKind tycon_kind
- (foldr mkTcArrowKind mkTcTypeKind tyvar_kinds)
- `thenTc_`
-
- -- Walk the condecls
- mapTc (tcConDecl rec_tycon rec_tyvars ctxt) con_decls
- `thenTc` \ con_ids ->
+tcTyDecl1 :: RecFlag -> RecTcEnv -> RenamedTyClDecl -> TcM (Name, TyThingDetails)
+tcTyDecl1 is_rec unf_env (TySynonym {tcdName = tycon_name, tcdSynRhs = rhs})
+ = tcLookupTyCon tycon_name `thenNF_Tc` \ tycon ->
+ tcExtendTyVarEnv (tyConTyVars tycon) $
+ tcHsRecType is_rec rhs `thenTc` \ rhs_ty ->
+ -- Note tcHsRecType not tcHsRecSigType; 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 is_rec unf_env (TyData {tcdND = new_or_data, tcdCtxt = context,
+ tcdName = tycon_name, tcdCons = con_decls})
+ = tcLookupTyCon tycon_name `thenNF_Tc` \ tycon ->
let
- -- Construct the tycon
- final_tycon_kind :: Kind -- NB not TcKind!
- final_tycon_kind = foldr (mkArrowKind . getTyVarKind) mkBoxedTypeKind rec_tyvars
-
- tycon = mkDataTyCon (getName tycon_name)
- final_tycon_kind
- rec_tyvars
- ctxt
- con_ids
- derived_classes
- data_or_new
+ tyvars = tyConTyVars tycon
in
- returnTc tycon
-
-tc_derivs Nothing = returnNF_Tc []
-tc_derivs (Just ds) = mapNF_Tc tc_deriv ds
+ tcExtendTyVarEnv tyvars $
-tc_deriv name
- = tcLookupClass name `thenNF_Tc` \ (_, clas) ->
- returnNF_Tc clas
+ -- Typecheck the pieces
+ tcRecTheta is_rec context `thenTc` \ ctxt ->
+ mapTc (tcConDecl is_rec new_or_data tycon tyvars ctxt) con_decls `thenTc` \ data_cons ->
+ tcRecordSelectors is_rec unf_env tycon data_cons `thenTc` \ sel_ids ->
+ returnTc (tycon_name, DataTyDetails ctxt data_cons sel_ids)
\end{code}
-Generating selector bindings for record delarations
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
\begin{code}
-tcRecordSelectors :: TyCon -> TcM s ([Id], TcHsBinds s)
-tcRecordSelectors tycon
- = mapAndUnzipTc (tcRecordSelector tycon) groups `thenTc` \ (ids, binds) ->
- returnTc (ids, SingleBind (NonRecBind (foldr AndMonoBinds EmptyMonoBinds binds)))
- where
- data_cons = tyConDataCons tycon
- fields = [ (con, field) | con <- data_cons,
- field <- dataConFieldLabels con
- ]
+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
- -- groups is list of fields that share a common name
- groups = equivClasses cmp_name fields
- cmp_name (_, field1) (_, field2)
- = fieldLabelName field1 `cmp` fieldLabelName field2
+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
+ }
\end{code}
-We're going to build a record selector that looks like this:
-
- data T a b c = T1 { op :: a, ...}
- | T2 { op :: a, ...}
- | T3
-
- sel :: forall a b c. T a b c -> a
- sel = /\ a b c -> \ T1 { sel = x } -> x
- T2 { sel = 2 } -> x
-
-Note that the selector Id itself is used as the field
-label; it has to be an Id, you see!
-
-\begin{code}
-tcRecordSelector tycon fields@((first_con, first_field_label) : other_fields)
- = panic "tcRecordSelector: don't typecheck"
-{-
- = let
- field_ty = fieldLabelType first_field_label
- field_name = fieldLabelName first_field_label
- other_tys = [fieldLabelType fl | (_, fl) <- fields]
- (tyvars, _, _, _) = dataConSig first_con
- -- tyvars of first_con may be free in first_ty
- in
-
- -- 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 (eqTy field_ty) other_tys)
- (fieldTypeMisMatch field_name) `thenTc_`
-
- -- Create an Id for the field itself
- tcInstTyVars tyvars `thenNF_Tc` \ (tyvars', tyvar_tys, tenv) ->
- tcInstType tenv field_ty `thenNF_Tc` \ field_ty' ->
- let
- data_ty' = applyTyCon tycon tyvar_tys
- in
- newLocalId SLIT("x") field_ty' `thenNF_Tc` \ field_id ->
- newLocalId SLIT("r") data_ty' `thenNF_Tc` \ record_id ->
- -- Now build the selector
- let
- tycon_src_loc = getSrcLoc tycon
-
- selector_ty = mkForAllTys tyvars' $
- mkFunTy data_ty' $
- field_ty'
-
- selector_id = mkRecordSelId first_field_label selector_ty
-
- -- HsSyn is dreadfully verbose for defining the selector!
- selector_rhs = mkHsTyLam tyvars' $
- HsLam $
- PatMatch (VarPat record_id) $
- GRHSMatch $
- GRHSsAndBindsOut [OtherwiseGRHS selector_body tycon_src_loc]
- EmptyBinds field_ty'
-
- selector_body = HsCase (HsVar record_id) (map mk_match fields) tycon_src_loc
-
- mk_match (con_id, field_label)
- = PatMatch (RecPat con_id data_ty' [(selector_id, VarPat field_id, False)]) $
- GRHSMatch $
- GRHSsAndBindsOut [OtherwiseGRHS (HsVar field_id)
- (getSrcLoc (fieldLabelName field_label))]
- EmptyBinds
- field_ty'
- in
- returnTc (selector_id, VarMonoBind selector_id selector_rhs)
--}
-\end{code}
+%************************************************************************
+%* *
+\subsection{Kind and type check constructors}
+%* *
+%************************************************************************
-Constructors
-~~~~~~~~~~~~
\begin{code}
-tcConDecl :: TyCon -> [TyVar] -> [(Class,Type)] -> RenamedConDecl -> TcM s Id
-
-tcConDecl tycon tyvars ctxt (ConDecl name btys src_loc)
- = tcDataCon tycon tyvars ctxt name btys src_loc
-
-tcConDecl tycon tyvars ctxt (ConOpDecl bty1 op bty2 src_loc)
- = tcDataCon tycon tyvars ctxt op [bty1,bty2] src_loc
-
-tcConDecl tycon tyvars ctxt (NewConDecl name ty src_loc)
- = tcAddSrcLoc src_loc $
- tcMonoType ty `thenTc` \ arg_ty ->
- let
- data_con = mkDataCon (getName name)
- [NotMarkedStrict]
- [{- No labelled fields -}]
- tyvars
- ctxt
- [arg_ty]
- tycon
- -- nullSpecEnv
- in
- returnTc data_con
-
-tcConDecl tycon tyvars ctxt (RecConDecl name fields src_loc)
- = tcAddSrcLoc src_loc $
- mapTc tcField fields `thenTc` \ field_label_infos_s ->
- let
- field_label_infos = concat field_label_infos_s
- stricts = [strict | (_, _, strict) <- field_label_infos]
- arg_tys = [ty | (_, ty, _) <- field_label_infos]
-
- field_labels = [ mkFieldLabel (getName name) ty tag
- | ((name, ty, _), tag) <- field_label_infos `zip` allFieldLabelTags
+kcConDetails :: NewOrData -> RenamedContext -> ConDetails Name -> TcM ()
+kcConDetails new_or_data ex_ctxt details
+ = kcHsContext ex_ctxt `thenTc_`
+ mapTc_ kc_sig_type (conDetailsTys details)
+ where
+ 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 :: RecFlag -> NewOrData -> TyCon -> [TyVar] -> ThetaType -> RenamedConDecl -> TcM DataCon
+
+tcConDecl is_rec new_or_data tycon tyvars ctxt (ConDecl name wkr_name ex_tvs ex_ctxt details src_loc)
+ = tcAddSrcLoc src_loc $
+ tcHsTyVars ex_tvs (kcConDetails new_or_data ex_ctxt details) $ \ ex_tyvars ->
+ tcRecTheta is_rec 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_datacon ex_tyvars ex_theta btys
+ = let
+ arg_stricts = map getBangStrictness btys
+ tys = map getBangType btys
+ in
+ mapTc (tcHsRecType is_rec) tys `thenTc` \ arg_tys ->
+ mk_data_con ex_tyvars ex_theta arg_stricts arg_tys []
+
+ tc_rec_con ex_tyvars ex_theta fields
+ = checkTc (null ex_tyvars) (exRecConErr name) `thenTc_`
+ mapTc tc_field (fields `zip` allFieldLabelTags) `thenTc` \ field_labels_s ->
+ 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
]
-
- data_con = mkDataCon (getName name)
- stricts
- field_labels
- tyvars
- (thinContext arg_tys ctxt)
+ in
+ mk_data_con ex_tyvars ex_theta arg_stricts
+ (map fieldLabelType field_labels) field_labels
+
+ tc_field ((field_label_names, bty), tag)
+ = tcHsRecType is_rec (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
+ = let
+ data_con = mkDataCon name arg_stricts fields
+ tyvars (thinContext arg_tys ctxt)
+ ex_tyvars ex_theta
arg_tys
- tycon
- -- nullSpecEnv
- in
- returnTc data_con
+ tycon data_con_id data_con_wrap_id
-tcField (field_label_names, bty)
- = tcMonoType (get_ty bty) `thenTc` \ field_ty ->
- returnTc [(name, field_ty, get_strictness bty) | name <- field_label_names]
-
-tcDataCon tycon tyvars ctxt name btys src_loc
- = tcAddSrcLoc src_loc $
- let
- stricts = map get_strictness btys
- tys = map get_ty btys
- in
- mapTc tcMonoType tys `thenTc` \ arg_tys ->
- let
- data_con = mkDataCon (getName name)
- stricts
- [{- No field labels -}]
- tyvars
- (thinContext arg_tys ctxt)
- arg_tys
- tycon
- -- nullSpecEnv
- in
- returnTc data_con
+ data_con_id = mkDataConId wkr_name data_con
+ data_con_wrap_id = mkDataConWrapId data_con
+ in
+ returnNF_Tc data_con
-- The context for a data constructor should be limited to
-- the type variables mentioned in the arg_tys
= filter in_arg_tys ctxt
where
arg_tyvars = tyVarsOfTypes arg_tys
- in_arg_tys (clas,ty) = getTyVar "tcDataCon" ty `elementOfTyVarSet` arg_tyvars
-
-get_strictness (Banged ty) = MarkedStrict
-get_strictness (Unbanged ty) = NotMarkedStrict
-
-get_ty (Banged ty) = ty
-get_ty (Unbanged ty) = ty
+ in_arg_tys pred = not $ isEmptyVarSet $
+ tyVarsOfPred pred `intersectVarSet` arg_tyvars
\end{code}
+%************************************************************************
+%* *
+\subsection{Record selectors}
+%* *
+%************************************************************************
-Errors and contexts
-~~~~~~~~~~~~~~~~~~~
\begin{code}
-tySynCtxt tycon_name sty
- = ppCat [ppStr "In the type declaration for", ppr sty tycon_name]
+tcRecordSelectors is_rec unf_env tycon data_cons
+ -- Omit the check that the fields have consistent types if
+ -- the group is recursive; TcTyClsDecls.tcGroup will repeat
+ -- with NonRecursive once we have tied the knot
+ | isRec is_rec = returnTc sel_ids
+ | otherwise = mapTc check groups `thenTc_`
+ returnTc sel_ids
+ where
+ fields = [ 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
+
+ sel_ids = [ mkRecordSelId tycon field unpack_id unpackUtf8_id
+ | (field : _) <- groups ]
+
+ check 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 (== 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
+
+ unpack_id = tcLookupRecId unf_env unpackCStringName
+ unpackUtf8_id = tcLookupRecId unf_env unpackCStringUtf8Name
+\end{code}
-tyDataCtxt tycon_name sty
- = ppCat [ppStr "In the data declaration for", ppr sty tycon_name]
-tyNewCtxt tycon_name sty
- = ppCat [ppStr "In the newtype declaration for", ppr sty tycon_name]
-fieldTypeMisMatch field_name sty
- = ppSep [ppStr "Declared types differ for field", ppr sty field_name]
+%************************************************************************
+%* *
+\subsection{Errors and contexts}
+%* *
+%************************************************************************
+
+
+\begin{code}
+fieldTypeMisMatch 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")
+ $$
+ (ptext SLIT("In the declaration of data constructor") <+> ppr name)
\end{code}
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