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, tcHsTyVars, tcClassContext,
24 kcHsContext, kcHsSigType
26 import TcEnv ( tcExtendTyVarEnv,
27 tcLookupTyCon, tcLookupClass, tcLookupGlobalId,
28 TyThing(..), TyThingDetails(..)
32 import Class ( ClassContext )
33 import DataCon ( DataCon, mkDataCon,
34 dataConFieldLabels, dataConId, dataConWrapId,
35 markedStrict, notMarkedStrict, markedUnboxed, dataConRepType
37 import MkId ( mkDataConId, mkDataConWrapId, mkRecordSelId )
39 import Var ( Id, TyVar )
40 import Name ( Name, isLocallyDefined, NamedThing(..) )
42 import TyCon ( TyCon, isSynTyCon, isNewTyCon,
43 tyConDataConsIfAvailable, tyConTyVars, tyConGenIds
45 import Type ( tyVarsOfTypes, splitFunTy, applyTys,
46 mkTyConApp, mkTyVarTys, mkForAllTys,
47 splitAlgTyConApp_maybe, Type
49 import TysWiredIn ( unitTy )
50 import VarSet ( intersectVarSet, isEmptyVarSet )
51 import PrelNames ( unpackCStringName, unpackCStringUtf8Name )
52 import ListSetOps ( equivClasses )
55 %************************************************************************
57 \subsection{Type checking}
59 %************************************************************************
62 tcTyDecl1 :: RenamedTyClDecl -> TcM (Name, TyThingDetails)
63 tcTyDecl1 (TySynonym tycon_name tyvar_names rhs src_loc)
64 = tcLookupTyCon tycon_name `thenNF_Tc` \ tycon ->
65 tcExtendTyVarEnv (tyConTyVars tycon) $
66 tcHsType rhs `thenTc` \ rhs_ty ->
67 -- Note tcHsType not tcHsSigType; we allow type synonyms
68 -- that aren't types; e.g. type List = []
70 -- If the RHS mentions tyvars that aren't in scope, we'll
71 -- quantify over them:
73 -- will become type T = forall a. a->a
75 -- With gla-exts that's right, but for H98 we should complain.
76 -- We can now do that here without falling into
77 -- a black hole, we still do it in rnDecl (TySynonym case)
79 returnTc (tycon_name, SynTyDetails rhs_ty)
81 tcTyDecl1 (TyData new_or_data context tycon_name _ con_decls _ derivings _ src_loc name1 name2)
82 = tcLookupTyCon tycon_name `thenNF_Tc` \ tycon ->
84 tyvars = tyConTyVars tycon
86 tcExtendTyVarEnv tyvars $
88 -- Typecheck the pieces
89 tcClassContext context `thenTc` \ ctxt ->
90 tc_derivs derivings `thenTc` \ derived_classes ->
91 mapTc (tcConDecl new_or_data tycon tyvars ctxt) con_decls `thenTc` \ data_cons ->
93 returnTc (tycon_name, DataTyDetails ctxt data_cons derived_classes)
95 tc_derivs Nothing = returnTc []
96 tc_derivs (Just ds) = mapTc tcLookupClass ds
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 ()
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 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 tcHsTyVars ex_tvs (kcConDetails ex_ctxt details) $ \ ex_tyvars ->
146 tcClassContext ex_ctxt `thenTc` \ ex_theta ->
148 VanillaCon btys -> tc_datacon ex_tyvars ex_theta btys
149 InfixCon bty1 bty2 -> tc_datacon ex_tyvars ex_theta [bty1,bty2]
150 RecCon fields -> tc_rec_con ex_tyvars ex_theta fields
152 tc_sig_type = case new_or_data of
153 DataType -> tcHsSigType
154 NewType -> tcHsBoxedSigType
155 -- Can't allow an unboxed type here, because we're effectively
156 -- going to remove the constructor while coercing it to a boxed type.
158 tc_datacon ex_tyvars ex_theta btys
160 arg_stricts = map getBangStrictness btys
161 tys = map getBangType btys
163 mapTc tc_sig_type tys `thenTc` \ arg_tys ->
164 mk_data_con ex_tyvars ex_theta arg_stricts arg_tys []
166 tc_rec_con ex_tyvars ex_theta fields
167 = checkTc (null ex_tyvars) (exRecConErr name) `thenTc_`
168 mapTc tc_field (fields `zip` allFieldLabelTags) `thenTc` \ field_labels_s ->
170 field_labels = concat field_labels_s
171 arg_stricts = [str | (ns, bty) <- fields,
172 let str = getBangStrictness bty,
173 n <- ns -- One for each. E.g x,y,z :: !Int
176 mk_data_con ex_tyvars ex_theta arg_stricts
177 (map fieldLabelType field_labels) field_labels
179 tc_field ((field_label_names, bty), tag)
180 = tc_sig_type (getBangType bty) `thenTc` \ field_ty ->
181 returnTc [mkFieldLabel (getName name) tycon field_ty tag | name <- field_label_names]
183 mk_data_con ex_tyvars ex_theta arg_stricts arg_tys fields
185 data_con = mkDataCon name arg_stricts fields
186 tyvars (thinContext arg_tys ctxt)
189 tycon data_con_id data_con_wrap_id
191 data_con_id = mkDataConId wkr_name data_con
192 data_con_wrap_id = mkDataConWrapId data_con
196 -- The context for a data constructor should be limited to
197 -- the type variables mentioned in the arg_tys
198 thinContext arg_tys ctxt
199 = filter in_arg_tys ctxt
201 arg_tyvars = tyVarsOfTypes arg_tys
202 in_arg_tys (clas,tys) = not $ isEmptyVarSet $
203 tyVarsOfTypes tys `intersectVarSet` arg_tyvars
205 getBangStrictness (Banged _) = markedStrict
206 getBangStrictness (Unbanged _) = notMarkedStrict
207 getBangStrictness (Unpacked _) = markedUnboxed
212 %************************************************************************
214 \subsection{Generating constructor/selector bindings for data declarations}
216 %************************************************************************
219 mkImplicitDataBinds :: [TyCon] -> TcM ([Id], TcMonoBinds)
220 mkImplicitDataBinds [] = returnTc ([], EmptyMonoBinds)
221 mkImplicitDataBinds (tycon : tycons)
222 | isSynTyCon tycon = mkImplicitDataBinds tycons
223 | otherwise = mkImplicitDataBinds_one tycon `thenTc` \ (ids1, b1) ->
224 mkImplicitDataBinds tycons `thenTc` \ (ids2, b2) ->
225 returnTc (ids1++ids2, b1 `AndMonoBinds` b2)
227 mkImplicitDataBinds_one tycon
228 = mapTc (mkRecordSelector tycon) groups `thenTc` \ sel_ids ->
230 unf_ids = sel_ids ++ data_con_wrapper_ids ++ gen_ids
231 all_ids = map dataConId data_cons ++ unf_ids
233 -- For the locally-defined things
234 -- we need to turn the unfoldings inside the selector Ids into bindings,
235 -- and build bindigns for the constructor wrappers
236 binds | isLocallyDefined tycon = idsToMonoBinds unf_ids
237 | otherwise = EmptyMonoBinds
239 returnTc (all_ids, binds)
241 data_cons = tyConDataConsIfAvailable tycon
242 -- Abstract types mean we don't bring the
243 -- data cons into scope, which should be fine
244 gen_ids = tyConGenIds tycon
245 data_con_wrapper_ids = map dataConWrapId data_cons
247 fields = [ (con, field) | con <- data_cons,
248 field <- dataConFieldLabels con
251 -- groups is list of fields that share a common name
252 groups = equivClasses cmp_name fields
253 cmp_name (_, field1) (_, field2)
254 = fieldLabelName field1 `compare` fieldLabelName field2
258 mkRecordSelector tycon fields@((first_con, first_field_label) : other_fields)
259 -- These fields all have the same name, but are from
260 -- different constructors in the data type
261 -- Check that all the fields in the group have the same type
262 -- This check assumes that all the constructors of a given
263 -- data type use the same type variables
264 = checkTc (all (== field_ty) other_tys)
265 (fieldTypeMisMatch field_name) `thenTc_`
266 tcLookupGlobalId unpackCStringName `thenTc` \ unpack_id ->
267 tcLookupGlobalId unpackCStringUtf8Name `thenTc` \ unpackUtf8_id ->
268 returnTc (mkRecordSelId tycon first_field_label unpack_id unpackUtf8_id)
270 field_ty = fieldLabelType first_field_label
271 field_name = fieldLabelName first_field_label
272 other_tys = [fieldLabelType fl | (_, fl) <- other_fields]
279 fieldTypeMisMatch field_name
280 = sep [ptext SLIT("Declared types differ for field"), quotes (ppr field_name)]
283 = ptext SLIT("Can't combine named fields with locally-quantified type variables")
285 (ptext SLIT("In the declaration of data constructor") <+> ppr name)