%
-% (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,
+ tcTyDecl, kcTyDecl,
tcConDecl,
- mkDataBinds
+ mkImplicitDataBinds, mkNewTyConRep
) 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 ( MonoBinds(..),
+ TyClDecl(..), ConDecl(..), ConDetails(..), BangType(..),
+ andMonoBindList
)
-import TcHsSyn ( mkHsTyLam, 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 RnHsSyn ( RenamedTyClDecl, RenamedConDecl )
+import TcHsSyn ( TcMonoBinds, idsToMonoBinds )
+import BasicTypes ( RecFlag(..), NewOrData(..) )
+
+import TcMonoType ( tcExtendTopTyVarScope, tcExtendTyVarScope,
+ tcHsTypeKind, kcHsType, tcHsTopType, tcHsTopBoxedType,
+ tcContext, tcHsTopTypeKind
)
+import TcType ( zonkTcTyVarToTyVar, zonkTcClassConstraints )
+import TcEnv ( tcLookupTy, tcLookupValueByKey, TcTyThing(..) )
import TcMonad
-import TcKind ( TcKind, unifyKind, mkTcArrowKind, mkTcTypeKind )
+import TcUnify ( unifyKind )
-import Class ( GenClass{-instance Eq-} )
-import Id ( mkDataCon, dataConSig, mkRecordSelId,
- dataConFieldLabels, dataConStrictMarks,
- StrictnessMark(..),
- GenId{-instance NamedThing-}
+import Class ( Class )
+import DataCon ( DataCon, mkDataCon, isNullaryDataCon,
+ dataConFieldLabels, dataConId, dataConWrapId,
+ markedStrict, notMarkedStrict, markedUnboxed, dataConRepType
)
+import MkId ( mkDataConId, mkDataConWrapId, mkRecordSelId )
import FieldLabel
-import Kind ( Kind, mkArrowKind, mkBoxedTypeKind )
-import SpecEnv ( SpecEnv(..), nullSpecEnv )
-import Name ( nameSrcLoc, isLocallyDefinedName, getSrcLoc,
- Name{-instance Ord3-}
+import Var ( Id, TyVar )
+import Name ( Name, isLocallyDefined, OccName, NamedThing(..), nameUnique )
+import Outputable
+import TyCon ( TyCon, AlgTyConFlavour(..), ArgVrcs, mkSynTyCon, mkAlgTyCon,
+ tyConDataConsIfAvailable, tyConTyVars,
+ isSynTyCon, isNewTyCon
)
-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 Type ( getTyVar, tyVarsOfTypes, splitFunTy, applyTys,
+ mkTyConApp, mkTyVarTys, mkForAllTys, mkFunTy,
+ mkTyVarTy, splitAlgTyConApp_maybe,
+ mkArrowKind, mkArrowKinds, boxedTypeKind,
+ isUnboxedType, Type, ThetaType, classesOfPreds
)
-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 )
+import TysWiredIn ( unitTy )
+import Var ( tyVarKind )
+import VarSet ( intersectVarSet, isEmptyVarSet )
+import Unique ( unpackCStringIdKey )
+import Util ( equivClasses )
+import FiniteMap ( FiniteMap, lookupWithDefaultFM )
+import CmdLineOpts ( opt_GlasgowExts )
\end{code}
+%************************************************************************
+%* *
+\subsection{Kind checking}
+%* *
+%************************************************************************
+
\begin{code}
-tcTyDecl :: RenamedTyDecl -> TcM s TyCon
-\end{code}
+kcTyDecl :: RenamedTyClDecl -> TcM s ()
+
+kcTyDecl (TySynonym name tyvar_names rhs src_loc)
+ = tcLookupTy name `thenNF_Tc` \ (kind, _) ->
+ tcExtendTopTyVarScope kind tyvar_names $ \ _ result_kind ->
+ tcHsTypeKind rhs `thenTc` \ (rhs_kind, _) ->
+ unifyKind result_kind rhs_kind
+
+kcTyDecl (TyData _ context tycon_name tyvar_names con_decls _ _ _ src_loc)
+ = tcLookupTy tycon_name `thenNF_Tc` \ (kind, _) ->
+ tcExtendTopTyVarScope kind tyvar_names $ \ result_kind _ ->
+ tcContext context `thenTc_`
+ mapTc kcConDecl con_decls `thenTc_`
+ returnTc ()
+
+kcConDecl (ConDecl _ _ ex_tvs ex_ctxt details loc)
+ = tcAddSrcLoc loc (
+ tcExtendTyVarScope ex_tvs ( \ tyvars ->
+ tcContext ex_ctxt `thenTc_`
+ kc_con details `thenTc_`
+ returnTc ()
+ ))
+ where
+ kc_con (VanillaCon btys) = mapTc kc_bty btys `thenTc_` returnTc ()
+ kc_con (InfixCon bty1 bty2) = mapTc kc_bty [bty1,bty2] `thenTc_` returnTc ()
+ kc_con (NewCon ty _) = kcHsType ty
+ kc_con (RecCon flds) = mapTc kc_field flds `thenTc_` returnTc ()
-Type synonym decls
-~~~~~~~~~~~~~~~~~~
+ kc_bty (Banged ty) = kcHsType ty
+ kc_bty (Unbanged ty) = kcHsType ty
+ kc_bty (Unpacked ty) = kcHsType ty
-\begin{code}
-tcTyDecl (TySynonym tycon_name tyvar_names rhs src_loc)
- = tcAddSrcLoc src_loc $
- tcAddErrCtxt (tySynCtxt tycon_name) $
+ kc_field (_, bty) = kc_bty bty
+\end{code}
- -- 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) ->
+%************************************************************************
+%* *
+\subsection{Type checking}
+%* *
+%************************************************************************
- -- Unify tycon kind with (k1->...->kn->rhs)
- unifyKind tycon_kind
- (foldr mkTcArrowKind rhs_kind tyvar_kinds)
- `thenTc_`
+\begin{code}
+tcTyDecl :: RecFlag -> FiniteMap Name ArgVrcs -> RenamedTyClDecl -> TcM s (Name, TcTyThing)
+
+tcTyDecl is_rec rec_vrcs (TySynonym tycon_name tyvar_names rhs src_loc)
+ = tcLookupTy tycon_name `thenNF_Tc` \ (tycon_kind, ASynTyCon _ arity) ->
+ tcExtendTopTyVarScope tycon_kind tyvar_names $ \ tyvars _ ->
+ tcHsTopTypeKind rhs `thenTc` \ (_, rhs_ty) ->
+ -- If the RHS mentions tyvars that aren't in scope, we'll
+ -- quantify over them. With gla-exts that's right, but for H98
+ -- we should complain. We can't do that here without falling into
+ -- a black hole, so we do it in rnDecl (TySynonym case)
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
+ argvrcs = lookupWithDefaultFM rec_vrcs (pprPanic "tcTyDecl: argvrcs:" $ ppr tycon_name)
+ tycon_name
+ tycon = mkSynTyCon tycon_name tycon_kind arity tyvars rhs_ty argvrcs
in
- returnTc tycon
-\end{code}
+ returnTc (tycon_name, ASynTyCon tycon arity)
-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 is_rec rec_vrcs (TyData data_or_new context tycon_name tyvar_names con_decls nconstrs derivings pragmas src_loc)
+ = -- Lookup the pieces
+ tcLookupTy tycon_name `thenNF_Tc` \ (tycon_kind, ADataTyCon rec_tycon) ->
+ tcExtendTopTyVarScope tycon_kind tyvar_names $ \ tyvars _ ->
-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
+ -- Typecheck the pieces
+ tcContext context `thenTc` \ ctxt ->
+ let ctxt' = classesOfPreds ctxt in
+ mapTc (tcConDecl rec_tycon tyvars ctxt') con_decls `thenTc` \ data_cons ->
+ tc_derivs derivings `thenTc` \ derived_classes ->
-
-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 ->
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
+ flavour = case data_or_new of
+ NewType -> NewTyCon (mkNewTyConRep tycon)
+ DataType | all isNullaryDataCon data_cons -> EnumTyCon
+ | otherwise -> DataTyCon
+
+ argvrcs = lookupWithDefaultFM rec_vrcs (pprPanic "tcTyDecl: argvrcs:" $ ppr tycon_name)
+ tycon_name
+
+ tycon = mkAlgTyCon tycon_name tycon_kind tyvars ctxt' argvrcs
+ data_cons nconstrs
+ derived_classes
+ flavour is_rec
in
- returnTc tycon
-
-tc_derivs Nothing = returnNF_Tc []
-tc_derivs (Just ds) = mapNF_Tc tc_deriv ds
+ returnTc (tycon_name, ADataTyCon tycon)
+ where
+ tc_derivs Nothing = returnTc []
+ tc_derivs (Just ds) = mapTc tc_deriv ds
-tc_deriv name
- = tcLookupClass name `thenNF_Tc` \ (_, clas) ->
- returnNF_Tc clas
+ tc_deriv name = tcLookupTy name `thenTc` \ (_, AClass clas _) ->
+ returnTc clas
\end{code}
-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
- )
- 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 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.
+%************************************************************************
+%* *
+\subsection{Type check constructors}
+%* *
+%************************************************************************
\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
+tcConDecl :: TyCon -> [TyVar] -> [(Class,[Type])] -> RenamedConDecl -> TcM s DataCon
+
+tcConDecl tycon tyvars ctxt (ConDecl name wkr_name ex_tvs ex_ctxt details src_loc)
+ = tcAddSrcLoc src_loc $
+ tcExtendTyVarScope ex_tvs $ \ ex_tyvars ->
+ tcContext ex_ctxt `thenTc` \ ex_theta ->
+ let
+ ex_ctxt' = classesOfPreds ex_theta
in
- newLocalIds (take n_args (repeat SLIT("con"))) arg_tys `thenNF_Tc` {- \ pre_zonk_args ->
- mapNF_Tc zonkId pre_zonk_args `thenNF_Tc` -} \ args ->
+ tc_con_decl_help tycon tyvars ctxt name wkr_name ex_tyvars ex_ctxt' details
+
+tc_con_decl_help tycon tyvars ctxt name wkr_name ex_tyvars ex_theta details
+ = case details of
+ VanillaCon btys -> tc_datacon btys
+ InfixCon bty1 bty2 -> tc_datacon [bty1,bty2]
+ NewCon ty mb_f -> tc_newcon ty mb_f
+ RecCon fields -> tc_rec_con fields
+ where
+ tc_datacon btys
+ = let
+ arg_stricts = map get_strictness btys
+ tys = map get_pty btys
+ in
+ mapTc tcHsTopType tys `thenTc` \ arg_tys ->
+ mk_data_con arg_stricts arg_tys []
+
+ tc_newcon ty mb_f
+ = tcHsTopBoxedType ty `thenTc` \ arg_ty ->
+ -- can't allow an unboxed type here, because we're effectively
+ -- going to remove the constructor while coercing it to a boxed type.
+ let
+ field_label =
+ case mb_f of
+ Nothing -> []
+ Just f -> [mkFieldLabel (getName f) tycon arg_ty (head allFieldLabelTags)]
+ in
+ mk_data_con [notMarkedStrict] [arg_ty] field_label
+
+ tc_rec_con fields
+ = checkTc (null ex_tyvars) (exRecConErr name) `thenTc_`
+ mapTc tc_field fields `thenTc` \ field_label_infos_s ->
+ let
+ field_label_infos = concat field_label_infos_s
+ arg_stricts = [strict | (_, _, strict) <- field_label_infos]
+ arg_tys = [ty | (_, ty, _) <- field_label_infos]
+
+ field_labels = [ mkFieldLabel (getName name) tycon ty tag
+ | ((name, ty, _), tag) <- field_label_infos `zip` allFieldLabelTags ]
+ in
+ mk_data_con arg_stricts arg_tys field_labels
+
+ tc_field (field_label_names, bty)
+ = tcHsTopType (get_pty bty) `thenTc` \ field_ty ->
+ returnTc [(name, field_ty, get_strictness bty) | name <- field_label_names]
+
+ mk_data_con arg_stricts arg_tys fields
+ = -- Now we've checked all the field types we must
+ -- zonk the existential tyvars to finish the kind
+ -- inference on their kinds, and commit them to being
+ -- immutable type variables. (The top-level tyvars are
+ -- already fixed, by the preceding kind-inference pass.)
+ mapNF_Tc zonkTcTyVarToTyVar ex_tyvars `thenNF_Tc` \ ex_tyvars' ->
+ zonkTcClassConstraints ex_theta `thenNF_Tc` \ ex_theta' ->
+ 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
- -- 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_`
+-- The context for a data constructor should be limited to
+-- the type variables mentioned in the arg_tys
+thinContext arg_tys ctxt
+ = filter in_arg_tys ctxt
+ where
+ arg_tyvars = tyVarsOfTypes arg_tys
+ in_arg_tys (clas,tys) = not $ isEmptyVarSet $
+ tyVarsOfTypes tys `intersectVarSet` arg_tyvars
+
+get_strictness (Banged _) = markedStrict
+get_strictness (Unbanged _) = notMarkedStrict
+get_strictness (Unpacked _) = markedUnboxed
- -- Build the data constructor
- let
- con_rhs = mkHsTyLam tyvars $
- DictLam dicts $
- mk_pat_match args $
- mk_case strict_args $
- HsCon con_id arg_tys (map HsVar args)
+get_pty (Banged ty) = ty
+get_pty (Unbanged ty) = ty
+get_pty (Unpacked ty) = ty
+\end{code}
- 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
+%************************************************************************
+%* *
+\subsection{Generating constructor/selector bindings for data declarations}
+%* *
+%************************************************************************
- returnTc (con_id, VarMonoBind (RealId con_id) con_rhs)
-\end{code}
-
-We're going to build a record selector that looks like this:
+\begin{code}
+mkImplicitDataBinds :: [TyCon] -> TcM s ([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
+ 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
- data T a b c = T1 { op :: a, ...}
- | T2 { op :: a, ...}
- | T3
+ data_con_wrapper_ids = map dataConWrapId data_cons
- sel :: forall a b c. T a b c -> a
- sel = /\ a b c -> \ T1 { sel = x } -> x
- T2 { sel = 2 } -> x
+ fields = [ (con, field) | con <- data_cons,
+ field <- dataConFieldLabels con
+ ]
-Note that the selector Id itself is used as the field
-label; it has to be an Id, you see!
+ -- 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)
- = 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
-
+ -- 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 (eqTy field_ty) other_tys)
+ = checkTc (all (== 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
- 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
-
--- The context for a data constructor should be limited to
--- the type variables mentioned in the arg_tys
-thinContext arg_tys ctxt
- = filter in_arg_tys ctxt
+ tcLookupValueByKey unpackCStringIdKey `thenTc` \ unpack_id ->
+ returnTc (mkRecordSelId tycon first_field_label unpack_id)
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
+ 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}
-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]
+fieldTypeMisMatch field_name
+ = sep [ptext SLIT("Declared types differ for field"), quotes (ppr field_name)]
-missingDataErr tyvar sty
- = ppStr "Missing `data' (???)" -- ToDo: improve
+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}
projects / ghc-hetmet.git / blobdiff