2 % (c) The AQUA Project, Glasgow University, 1996-1998
4 \section[TcTyDecls]{Typecheck type declarations}
10 mkImplicitDataBinds, mkNewTyConRep
13 #include "HsVersions.h"
15 import HsSyn ( MonoBinds(..),
16 TyClDecl(..), ConDecl(..), ConDetails(..), BangType(..),
19 import RnHsSyn ( RenamedTyClDecl, RenamedConDecl, RenamedContext )
20 import TcHsSyn ( TcMonoBinds, idsToMonoBinds )
21 import BasicTypes ( NewOrData(..) )
23 import TcMonoType ( tcHsType, tcHsSigType, tcHsBoxedSigType, kcTyVarScope, tcClassContext,
24 kcHsContext, kcHsSigType, mkImmutTyVars
26 import TcEnv ( tcExtendTyVarEnv, tcLookupTy, tcLookupValueByKey, TyThing(..), TyThingDetails(..) )
29 import Class ( ClassContext )
30 import DataCon ( DataCon, mkDataCon,
31 dataConFieldLabels, dataConId, dataConWrapId,
32 markedStrict, notMarkedStrict, markedUnboxed, dataConRepType
34 import MkId ( mkDataConId, mkDataConWrapId, mkRecordSelId )
36 import Var ( Id, TyVar )
37 import Name ( Name, isLocallyDefined, NamedThing(..) )
39 import TyCon ( TyCon, isSynTyCon, isNewTyCon,
40 tyConDataConsIfAvailable, tyConTyVars
42 import Type ( tyVarsOfTypes, splitFunTy, applyTys,
43 mkTyConApp, mkTyVarTys, mkForAllTys,
44 splitAlgTyConApp_maybe, Type
46 import TysWiredIn ( unitTy )
47 import VarSet ( intersectVarSet, isEmptyVarSet )
48 import Unique ( unpackCStringIdKey, unpackCStringUtf8IdKey )
49 import Util ( equivClasses )
52 %************************************************************************
54 \subsection{Type checking}
56 %************************************************************************
59 tcTyDecl1 :: RenamedTyClDecl -> TcM s (Name, TyThingDetails)
60 tcTyDecl1 (TySynonym tycon_name tyvar_names rhs src_loc)
61 = tcLookupTy tycon_name `thenNF_Tc` \ (ATyCon tycon) ->
62 tcExtendTyVarEnv (tyConTyVars tycon) $
63 tcHsType rhs `thenTc` \ rhs_ty ->
64 -- Note tcHsType not tcHsSigType; we allow type synonyms
65 -- that aren't types; e.g. type List = []
67 -- If the RHS mentions tyvars that aren't in scope, we'll
68 -- quantify over them:
70 -- will become type T = forall a. a->a
72 -- With gla-exts that's right, but for H98 we should complain.
73 -- We can now do that here without falling into
74 -- a black hole, we still do it in rnDecl (TySynonym case)
76 returnTc (tycon_name, SynTyDetails rhs_ty)
78 tcTyDecl1 (TyData new_or_data context tycon_name _ con_decls _ derivings _ src_loc)
79 = tcLookupTy tycon_name `thenNF_Tc` \ (ATyCon tycon) ->
81 tyvars = tyConTyVars tycon
83 tcExtendTyVarEnv tyvars $
85 -- Typecheck the pieces
86 tcClassContext context `thenTc` \ ctxt ->
87 tc_derivs derivings `thenTc` \ derived_classes ->
88 mapTc (tcConDecl new_or_data tycon tyvars ctxt) con_decls `thenTc` \ data_cons ->
90 returnTc (tycon_name, DataTyDetails ctxt data_cons derived_classes)
92 tc_derivs Nothing = returnTc []
93 tc_derivs (Just ds) = mapTc tc_deriv ds
95 tc_deriv name = tcLookupTy name `thenTc` \ (AClass clas) ->
100 mkNewTyConRep :: TyCon -> Type
101 -- Find the representation type for this newtype TyCon
102 -- The trick is to to deal correctly with recursive newtypes
103 -- such as newtype T = MkT T
106 = mkForAllTys tvs (loop [] (mkTyConApp tc (mkTyVarTys tvs)))
109 loop tcs ty = case splitAlgTyConApp_maybe ty of {
111 Just (tc, tys, data_cons) | not (isNewTyCon tc) -> ty
112 | tc `elem` tcs -> unitTy
115 case splitFunTy (applyTys (dataConRepType (head data_cons)) tys) of
116 (rep_ty, _) -> loop (tc:tcs) rep_ty
121 %************************************************************************
123 \subsection{Kind and type check constructors}
125 %************************************************************************
128 kcConDetails :: RenamedContext -> ConDetails Name -> TcM s ()
129 kcConDetails ex_ctxt details
130 = kcHsContext ex_ctxt `thenTc_`
131 kc_con_details details
133 kc_con_details (VanillaCon btys) = mapTc_ kc_bty btys
134 kc_con_details (InfixCon bty1 bty2) = mapTc_ kc_bty [bty1,bty2]
135 kc_con_details (RecCon flds) = mapTc_ kc_field flds
137 kc_field (_, bty) = kc_bty bty
139 kc_bty bty = kcHsSigType (getBangType bty)
141 tcConDecl :: NewOrData -> TyCon -> [TyVar] -> ClassContext -> RenamedConDecl -> TcM s DataCon
143 tcConDecl new_or_data tycon tyvars ctxt (ConDecl name wkr_name ex_tvs ex_ctxt details src_loc)
144 = tcAddSrcLoc src_loc $
145 kcTyVarScope ex_tvs (kcConDetails ex_ctxt details) `thenTc` \ ex_tv_kinds ->
147 ex_tyvars = mkImmutTyVars ex_tv_kinds
149 tcExtendTyVarEnv ex_tyvars $
150 tcClassContext ex_ctxt `thenTc` \ ex_theta ->
152 VanillaCon btys -> tc_datacon ex_tyvars ex_theta btys
153 InfixCon bty1 bty2 -> tc_datacon ex_tyvars ex_theta [bty1,bty2]
154 RecCon fields -> tc_rec_con ex_tyvars ex_theta fields
156 tc_sig_type = case new_or_data of
157 DataType -> tcHsSigType
158 NewType -> tcHsBoxedSigType
159 -- Can't allow an unboxed type here, because we're effectively
160 -- going to remove the constructor while coercing it to a boxed type.
162 tc_datacon ex_tyvars ex_theta btys
164 arg_stricts = map getBangStrictness btys
165 tys = map getBangType btys
167 mapTc tc_sig_type tys `thenTc` \ arg_tys ->
168 mk_data_con ex_tyvars ex_theta arg_stricts arg_tys []
170 tc_rec_con ex_tyvars ex_theta fields
171 = checkTc (null ex_tyvars) (exRecConErr name) `thenTc_`
172 mapTc tc_field (fields `zip` allFieldLabelTags) `thenTc` \ field_labels_s ->
174 field_labels = concat field_labels_s
175 arg_stricts = [str | (ns, bty) <- fields,
176 let str = getBangStrictness bty,
177 n <- ns -- One for each. E.g x,y,z :: !Int
180 mk_data_con ex_tyvars ex_theta arg_stricts
181 (map fieldLabelType field_labels) field_labels
183 tc_field ((field_label_names, bty), tag)
184 = tc_sig_type (getBangType bty) `thenTc` \ field_ty ->
185 returnTc [mkFieldLabel (getName name) tycon field_ty tag | name <- field_label_names]
187 mk_data_con ex_tyvars ex_theta arg_stricts arg_tys fields
189 data_con = mkDataCon name arg_stricts fields
190 tyvars (thinContext arg_tys ctxt)
193 tycon data_con_id data_con_wrap_id
195 data_con_id = mkDataConId wkr_name data_con
196 data_con_wrap_id = mkDataConWrapId data_con
200 -- The context for a data constructor should be limited to
201 -- the type variables mentioned in the arg_tys
202 thinContext arg_tys ctxt
203 = filter in_arg_tys ctxt
205 arg_tyvars = tyVarsOfTypes arg_tys
206 in_arg_tys (clas,tys) = not $ isEmptyVarSet $
207 tyVarsOfTypes tys `intersectVarSet` arg_tyvars
209 getBangStrictness (Banged _) = markedStrict
210 getBangStrictness (Unbanged _) = notMarkedStrict
211 getBangStrictness (Unpacked _) = markedUnboxed
216 %************************************************************************
218 \subsection{Generating constructor/selector bindings for data declarations}
220 %************************************************************************
223 mkImplicitDataBinds :: [TyCon] -> TcM s ([Id], TcMonoBinds)
224 mkImplicitDataBinds [] = returnTc ([], EmptyMonoBinds)
225 mkImplicitDataBinds (tycon : tycons)
226 | isSynTyCon tycon = mkImplicitDataBinds tycons
227 | otherwise = mkImplicitDataBinds_one tycon `thenTc` \ (ids1, b1) ->
228 mkImplicitDataBinds tycons `thenTc` \ (ids2, b2) ->
229 returnTc (ids1++ids2, b1 `AndMonoBinds` b2)
231 mkImplicitDataBinds_one tycon
232 = mapTc (mkRecordSelector tycon) groups `thenTc` \ sel_ids ->
234 unf_ids = sel_ids ++ data_con_wrapper_ids
235 all_ids = map dataConId data_cons ++ unf_ids
237 -- For the locally-defined things
238 -- we need to turn the unfoldings inside the selector Ids into bindings,
239 -- and build bindigns for the constructor wrappers
240 binds | isLocallyDefined tycon = idsToMonoBinds unf_ids
241 | otherwise = EmptyMonoBinds
243 returnTc (all_ids, binds)
245 data_cons = tyConDataConsIfAvailable tycon
246 -- Abstract types mean we don't bring the
247 -- data cons into scope, which should be fine
249 data_con_wrapper_ids = map dataConWrapId data_cons
251 fields = [ (con, field) | con <- data_cons,
252 field <- dataConFieldLabels con
255 -- groups is list of fields that share a common name
256 groups = equivClasses cmp_name fields
257 cmp_name (_, field1) (_, field2)
258 = fieldLabelName field1 `compare` fieldLabelName field2
262 mkRecordSelector tycon fields@((first_con, first_field_label) : other_fields)
263 -- These fields all have the same name, but are from
264 -- different constructors in the data type
265 -- Check that all the fields in the group have the same type
266 -- This check assumes that all the constructors of a given
267 -- data type use the same type variables
268 = checkTc (all (== field_ty) other_tys)
269 (fieldTypeMisMatch field_name) `thenTc_`
270 tcLookupValueByKey unpackCStringIdKey `thenTc` \ unpack_id ->
271 tcLookupValueByKey unpackCStringUtf8IdKey `thenTc` \ unpackUtf8_id ->
272 returnTc (mkRecordSelId tycon first_field_label unpack_id unpackUtf8_id)
274 field_ty = fieldLabelType first_field_label
275 field_name = fieldLabelName first_field_label
276 other_tys = [fieldLabelType fl | (_, fl) <- other_fields]
283 fieldTypeMisMatch field_name
284 = sep [ptext SLIT("Declared types differ for field"), quotes (ppr field_name)]
287 = ptext SLIT("Can't combine named fields with locally-quantified type variables")
289 (ptext SLIT("In the declaration of data constructor") <+> ppr name)