%
-% (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,
- mkDataBinds
- ) where
+module TcTyDecls ( tcTyDecl, kcConDetails ) where
-import Ubiq{-uitous-}
+#include "HsVersions.h"
-import HsSyn ( TyDecl(..), ConDecl(..), BangType(..), HsExpr(..),
- Match(..), GRHSsAndBinds(..), GRHS(..), OutPat(..),
- HsBinds(..), HsLit, Stmt, Qual, ArithSeqInfo,
- PolyType, Fake, InPat,
- Bind(..), MonoBinds(..), Sig,
- MonoType )
-import RnHsSyn ( RenamedTyDecl(..), RenamedConDecl(..),
- RnName{-instance Outputable-}
+import HsSyn ( TyClDecl(..), ConDecl(..), ConDetails(..),
+ getBangType, getBangStrictness, conDetailsTys
)
-import TcHsSyn ( mkHsTyLam, mkHsDictLam, tcIdType, zonkId,
- TcHsBinds(..), TcIdOcc(..)
- )
-import Inst ( newDicts, InstOrigin(..), Inst )
-import TcMonoType ( tcMonoTypeKind, tcMonoType, tcContext )
-import TcType ( tcInstTyVars, tcInstType, tcInstId )
-import TcEnv ( tcLookupTyCon, tcLookupTyVar, tcLookupClass,
- tcLookupClassByKey,
- newLocalId, newLocalIds
- )
-import TcMonad
-import TcKind ( TcKind, unifyKind, mkTcArrowKind, mkTcTypeKind )
+import RnHsSyn ( RenamedTyClDecl, RenamedConDecl, RenamedContext )
+import BasicTypes ( NewOrData(..) )
-import Class ( GenClass{-instance Eq-} )
-import Id ( mkDataCon, dataConSig, mkRecordSelId,
- dataConFieldLabels, dataConStrictMarks,
- StrictnessMark(..),
- GenId{-instance NamedThing-}
+import TcMonoType ( tcHsTyVars, tcHsTheta, tcHsType,
+ kcHsContext, kcHsSigType, kcHsLiftedSigType
)
-import FieldLabel
-import Kind ( Kind, mkArrowKind, mkBoxedTypeKind )
-import SpecEnv ( SpecEnv(..), nullSpecEnv )
-import Name ( nameSrcLoc, isLocallyDefinedName, getSrcLoc,
- Name{-instance Ord3-}
+import TcEnv ( tcExtendTyVarEnv,
+ tcLookupTyCon, tcLookupRecId,
+ TyThingDetails(..), RecTcEnv
)
-import Pretty
-import TyCon ( TyCon, NewOrData(..), mkSynTyCon, mkDataTyCon, isDataTyCon,
- tyConDataCons )
-import Type ( getTypeKind, getTyVar, tyVarsOfTypes, eqTy,
- applyTyCon, mkTyVarTys, mkForAllTys, mkFunTy,
- splitFunTy, mkTyVarTy, getTyVar_maybe
- )
-import TyVar ( getTyVarKind, elementOfTyVarSet, GenTyVar{-instance Eq-} )
-import Unique ( Unique {- instance Eq -}, dataClassKey )
-import UniqSet ( emptyUniqSet, mkUniqSet, uniqSetToList, unionManyUniqSets, UniqSet(..) )
-import Util ( equivClasses, zipEqual, panic, assertPanic )
-\end{code}
+import TcType ( tyVarsOfTypes, tyVarsOfPred, ThetaType )
+import TcMonad
-\begin{code}
-tcTyDecl :: RenamedTyDecl -> TcM s TyCon
+import DataCon ( DataCon, mkDataCon, dataConFieldLabels )
+import FieldLabel ( fieldLabelName, fieldLabelType, allFieldLabelTags, mkFieldLabel )
+import MkId ( mkDataConId, mkDataConWrapId, mkRecordSelId )
+import Var ( TyVar )
+import Name ( Name, NamedThing(..) )
+import Outputable
+import TyCon ( TyCon, DataConDetails(..), visibleDataCons,
+ tyConTyVars )
+import VarSet ( intersectVarSet, isEmptyVarSet )
+import PrelNames ( unpackCStringName, unpackCStringUtf8Name )
+import List ( nubBy )
\end{code}
-Type synonym decls
-~~~~~~~~~~~~~~~~~~
+%************************************************************************
+%* *
+\subsection{Type checking}
+%* *
+%************************************************************************
\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_`
+tcTyDecl :: RenamedTyClDecl -> TcM (Name, TyThingDetails)
+tcTyDecl (TySynonym {tcdName = tycon_name, tcdSynRhs = rhs})
+ = tcLookupTyCon tycon_name `thenNF_Tc` \ tycon ->
+ tcExtendTyVarEnv (tyConTyVars tycon) $
+ tcHsType rhs `thenTc` \ rhs_ty ->
+ returnTc (tycon_name, SynTyDetails rhs_ty)
+
+tcTyDecl (TyData {tcdND = new_or_data, tcdCtxt = context,
+ tcdName = tycon_name, tcdCons = con_decls})
+ = tcLookupTyCon tycon_name `thenNF_Tc` \ tycon ->
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
+ tyvars = tyConTyVars tycon
in
- returnTc tycon
-\end{code}
-
-Algebraic data and newtype decls
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-\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 ->
+ tcExtendTyVarEnv tyvars $
+ tcHsTheta context `thenTc` \ ctxt ->
+ tcConDecls new_or_data tycon tyvars ctxt con_decls `thenTc` \ data_cons ->
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
+ sel_ids = mkRecordSelectors tycon data_cons
in
- returnTc tycon
-
-tc_derivs Nothing = returnNF_Tc []
-tc_derivs (Just ds) = mapNF_Tc tc_deriv ds
+ returnTc (tycon_name, DataTyDetails ctxt data_cons sel_ids)
-tc_deriv name
- = tcLookupClass name `thenNF_Tc` \ (_, clas) ->
- returnNF_Tc clas
-\end{code}
+tcTyDecl (ForeignType {tcdName = tycon_name})
+ = returnTc (tycon_name, ForeignTyDetails)
-Generating constructor/selector bindings for data declarations
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-\begin{code}
-mkDataBinds :: TyCon -> TcM s ([Id], TcHsBinds s)
-mkDataBinds tycon
- = ASSERT( isDataTyCon tycon )
- mapAndUnzipTc mkConstructor data_cons `thenTc` \ (con_ids, con_binds) ->
- mapAndUnzipTc (mkRecordSelector tycon) groups `thenTc` \ (sel_ids, sel_binds) ->
- returnTc (con_ids ++ sel_ids,
- SingleBind $ NonRecBind $
- foldr AndMonoBinds
- (foldr AndMonoBinds EmptyMonoBinds con_binds)
- con_binds
- )
+mkRecordSelectors tycon data_cons
+ = -- We'll check later that fields with the same name
+ -- from different constructors have the same type.
+ [ mkRecordSelId tycon field
+ | field <- nubBy eq_name fields ]
where
- data_cons = tyConDataCons tycon
- 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 `cmp` fieldLabelName field2
-\end{code}
-
-We're going to build a constructor that looks like:
-
- data (Data a, C b) => T a b = T1 !a !Int b
-
- T1 = /\ a b ->
- \d1::Data a, d2::C b ->
- \p q r -> case p of { p ->
- case q of { q ->
- HsCon [a,b,c] [p,q,r]}}
-
-Notice that
-
-* d2 is thrown away --- a context in a data decl is used to make sure
- one *could* construct dictionaries at the site the constructor
- is used, but the dictionary isn't actually used.
-
-* We have to check that we can construct Data dictionaries for
- the types a and Int. Once we've done that we can throw d1 away too.
-
-* We use (case p of ...) to evaluate p, rather than "seq" because
- all that matters is that the arguments are evaluated. "seq" is
- very careful to preserve evaluation order, which we don't need
- to be here.
-
-\begin{code}
-mkConstructor con_id
- | not (isLocallyDefinedName (getName con_id))
- = returnTc (con_id, EmptyMonoBinds)
-
- | otherwise -- It is locally defined
- = tcInstId con_id `thenNF_Tc` \ (tyvars, theta, tau) ->
- newDicts DataDeclOrigin theta `thenNF_Tc` \ (_, dicts) ->
- let
- (arg_tys, result_ty) = splitFunTy tau
- n_args = length arg_tys
- in
- newLocalIds (take n_args (repeat SLIT("con"))) arg_tys `thenNF_Tc` {- \ pre_zonk_args ->
- mapNF_Tc zonkId pre_zonk_args `thenNF_Tc` -} \ args ->
-
- -- Check that all the types of all the strict
- -- arguments are in Data. This is trivially true of everything except
- -- type variables, for which we must check the context.
- let
- strict_marks = dataConStrictMarks con_id
- strict_args = [arg | (arg, MarkedStrict) <- args `zipEqual` strict_marks]
-
- data_tyvars = -- The tyvars in the constructor's context that are arguments
- -- to the Data class
- [getTyVar "mkConstructor" ty
- | (clas,ty) <- theta,
- uniqueOf clas == dataClassKey]
-
- check_data arg = case getTyVar_maybe (tcIdType arg) of
- Nothing -> returnTc () -- Not a tyvar, so OK
- Just tyvar -> checkTc (tyvar `elem` data_tyvars) (missingDataErr tyvar)
- in
- mapTc check_data strict_args `thenTc_`
-
- -- Build the data constructor
- let
- con_rhs = mkHsTyLam tyvars $
- mkHsDictLam dicts $
- mk_pat_match args $
- mk_case strict_args $
- HsCon con_id arg_tys (map HsVar args)
-
- mk_pat_match [] body = body
- mk_pat_match (arg:args) body = HsLam (PatMatch (VarPat arg) (SimpleMatch (mk_pat_match args body)))
-
- mk_case [] body = body
- mk_case (arg:args) body = HsCase (HsVar arg)
- [PatMatch (VarPat arg) (SimpleMatch (mk_case args body))]
- src_loc
-
- src_loc = nameSrcLoc (getName con_id)
- in
-
- returnTc (con_id, VarMonoBind (RealId con_id) con_rhs)
+ fields = [ field | con <- visibleDataCons data_cons,
+ field <- dataConFieldLabels con ]
+ eq_name field1 field2 = fieldLabelName field1 == fieldLabelName field2
\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!
+%************************************************************************
+%* *
+\subsection{Kind and type check constructors}
+%* *
+%************************************************************************
\begin{code}
-mkRecordSelector tycon fields@((first_con, first_field_label) : other_fields)
- = let
- field_ty = fieldLabelType first_field_label
- field_name = fieldLabelName first_field_label
- other_tys = [fieldLabelType fl | (_, fl) <- other_fields]
- (tyvars, _, _, _) = dataConSig first_con
- data_ty = applyTyCon tycon (mkTyVarTys tyvars)
- -- tyvars of first_con may be free in field_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_`
+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.
+
+
+tcConDecls :: NewOrData -> TyCon -> [TyVar] -> ThetaType
+ -> DataConDetails RenamedConDecl -> TcM (DataConDetails DataCon)
+
+tcConDecls new_or_data tycon tyvars ctxt con_decls
+ = case con_decls of
+ Unknown -> returnTc Unknown
+ HasCons n -> returnTc (HasCons n)
+ DataCons cs -> mapTc tc_con_decl cs `thenTc` \ data_cons ->
+ returnTc (DataCons data_cons)
+ where
+ tc_con_decl (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 ->
+ 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_datacon ex_tyvars ex_theta btys
+ = mapTc tcHsType (map getBangType btys) `thenTc` \ arg_tys ->
+ mk_data_con ex_tyvars ex_theta (map getBangStrictness btys) arg_tys []
- -- 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
- selector_ty :: Type
- selector_ty = mkForAllTys tyvars $
- mkFunTy data_ty $
- field_ty
-
- selector_id :: Id
- 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) $
- SimpleMatch $
- selector_body
-
- selector_body = HsCase (HsVar record_id) (map mk_match fields) (getSrcLoc tycon)
-
- mk_match (con_id, field_label)
- = PatMatch (RecPat con_id data_ty' [(RealId selector_id, VarPat field_id, False)]) $
- SimpleMatch $
- HsVar field_id
- in
- returnTc (selector_id, if isLocallyDefinedName (getName tycon)
- then VarMonoBind (RealId selector_id) selector_rhs
- else EmptyMonoBinds)
-\end{code}
-
-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
- ]
-
- data_con = mkDataCon (getName name)
- stricts
- field_labels
- tyvars
- (thinContext arg_tys ctxt)
- arg_tys
- tycon
- -- nullSpecEnv
- in
- returnTc data_con
-
-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
+ 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
+ ]
+ in
+ mk_data_con ex_tyvars ex_theta arg_stricts
+ (map fieldLabelType field_labels) field_labels
+
+ tc_field ((field_label_names, bty), tag)
+ = 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
+ = let
+ data_con = mkDataCon name arg_stricts fields
+ tyvars (thinContext arg_tys ctxt)
+ ex_tyvars ex_theta
+ arg_tys
+ tycon data_con_id data_con_wrap_id
+
+ 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{Errors and contexts}
+%* *
+%************************************************************************
-Errors and contexts
-~~~~~~~~~~~~~~~~~~~
-\begin{code}
-tySynCtxt tycon_name sty
- = ppCat [ppStr "In the type declaration for", ppr sty tycon_name]
-
-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]
-missingDataErr tyvar sty
- = ppStr "Missing `data' (???)" -- ToDo: improve
+\begin{code}
+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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