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,
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 Module ( Module )
41 import Name ( Name, NamedThing(..), isFrom )
43 import TyCon ( TyCon, isSynTyCon, isNewTyCon,
44 tyConDataConsIfAvailable, tyConTyVars, tyConGenIds
46 import Type ( tyVarsOfTypes, splitFunTy, applyTys,
47 mkTyConApp, mkTyVarTys, mkForAllTys,
48 splitAlgTyConApp_maybe, Type
50 import TysWiredIn ( unitTy )
51 import VarSet ( intersectVarSet, isEmptyVarSet )
52 import PrelNames ( unpackCStringName, unpackCStringUtf8Name )
53 import ListSetOps ( equivClasses )
56 %************************************************************************
58 \subsection{Type checking}
60 %************************************************************************
63 tcTyDecl1 :: RenamedTyClDecl -> TcM (Name, TyThingDetails)
64 tcTyDecl1 (TySynonym tycon_name tyvar_names rhs src_loc)
65 = tcLookupTyCon tycon_name `thenNF_Tc` \ tycon ->
66 tcExtendTyVarEnv (tyConTyVars tycon) $
67 tcHsType rhs `thenTc` \ rhs_ty ->
68 -- Note tcHsType not tcHsSigType; we allow type synonyms
69 -- that aren't types; e.g. type List = []
71 -- If the RHS mentions tyvars that aren't in scope, we'll
72 -- quantify over them:
74 -- will become type T = forall a. a->a
76 -- With gla-exts that's right, but for H98 we should complain.
77 -- We can now do that here without falling into
78 -- a black hole, we still do it in rnDecl (TySynonym case)
80 returnTc (tycon_name, SynTyDetails rhs_ty)
82 tcTyDecl1 (TyData new_or_data context tycon_name _ con_decls _ derivings src_loc name1 name2)
83 = tcLookupTyCon tycon_name `thenNF_Tc` \ tycon ->
85 tyvars = tyConTyVars tycon
87 tcExtendTyVarEnv tyvars $
89 -- Typecheck the pieces
90 tcClassContext context `thenTc` \ ctxt ->
91 tc_derivs derivings `thenTc` \ derived_classes ->
92 mapTc (tcConDecl new_or_data tycon tyvars ctxt) con_decls `thenTc` \ data_cons ->
94 returnTc (tycon_name, DataTyDetails ctxt data_cons derived_classes)
96 tc_derivs Nothing = returnTc []
97 tc_derivs (Just ds) = mapTc tcLookupClass ds
101 mkNewTyConRep :: TyCon -> Type
102 -- Find the representation type for this newtype TyCon
103 -- The trick is to to deal correctly with recursive newtypes
104 -- such as newtype T = MkT T
107 = mkForAllTys tvs (loop [] (mkTyConApp tc (mkTyVarTys tvs)))
110 loop tcs ty = case splitAlgTyConApp_maybe ty of {
112 Just (tc, tys, data_cons) | not (isNewTyCon tc) -> ty
113 | tc `elem` tcs -> unitTy
116 case splitFunTy (applyTys (dataConRepType (head data_cons)) tys) of
117 (rep_ty, _) -> loop (tc:tcs) rep_ty
122 %************************************************************************
124 \subsection{Kind and type check constructors}
126 %************************************************************************
129 kcConDetails :: RenamedContext -> ConDetails Name -> TcM ()
130 kcConDetails ex_ctxt details
131 = kcHsContext ex_ctxt `thenTc_`
132 kc_con_details details
134 kc_con_details (VanillaCon btys) = mapTc_ kc_bty btys
135 kc_con_details (InfixCon bty1 bty2) = mapTc_ kc_bty [bty1,bty2]
136 kc_con_details (RecCon flds) = mapTc_ kc_field flds
138 kc_field (_, bty) = kc_bty bty
140 kc_bty bty = kcHsSigType (getBangType bty)
142 tcConDecl :: NewOrData -> TyCon -> [TyVar] -> ClassContext -> RenamedConDecl -> TcM DataCon
144 tcConDecl new_or_data tycon tyvars ctxt (ConDecl name wkr_name ex_tvs ex_ctxt details src_loc)
145 = tcAddSrcLoc src_loc $
146 tcHsTyVars ex_tvs (kcConDetails ex_ctxt details) $ \ ex_tyvars ->
147 tcClassContext ex_ctxt `thenTc` \ ex_theta ->
149 VanillaCon btys -> tc_datacon ex_tyvars ex_theta btys
150 InfixCon bty1 bty2 -> tc_datacon ex_tyvars ex_theta [bty1,bty2]
151 RecCon fields -> tc_rec_con ex_tyvars ex_theta fields
153 tc_sig_type = case new_or_data of
154 DataType -> tcHsSigType
155 NewType -> tcHsBoxedSigType
156 -- Can't allow an unboxed type here, because we're effectively
157 -- going to remove the constructor while coercing it to a boxed type.
159 tc_datacon ex_tyvars ex_theta btys
161 arg_stricts = map getBangStrictness btys
162 tys = map getBangType btys
164 mapTc tc_sig_type tys `thenTc` \ arg_tys ->
165 mk_data_con ex_tyvars ex_theta arg_stricts arg_tys []
167 tc_rec_con ex_tyvars ex_theta fields
168 = checkTc (null ex_tyvars) (exRecConErr name) `thenTc_`
169 mapTc tc_field (fields `zip` allFieldLabelTags) `thenTc` \ field_labels_s ->
171 field_labels = concat field_labels_s
172 arg_stricts = [str | (ns, bty) <- fields,
173 let str = getBangStrictness bty,
174 n <- ns -- One for each. E.g x,y,z :: !Int
177 mk_data_con ex_tyvars ex_theta arg_stricts
178 (map fieldLabelType field_labels) field_labels
180 tc_field ((field_label_names, bty), tag)
181 = tc_sig_type (getBangType bty) `thenTc` \ field_ty ->
182 returnTc [mkFieldLabel (getName name) tycon field_ty tag | name <- field_label_names]
184 mk_data_con ex_tyvars ex_theta arg_stricts arg_tys fields
186 data_con = mkDataCon name arg_stricts fields
187 tyvars (thinContext arg_tys ctxt)
190 tycon data_con_id data_con_wrap_id
192 data_con_id = mkDataConId wkr_name data_con
193 data_con_wrap_id = mkDataConWrapId data_con
197 -- The context for a data constructor should be limited to
198 -- the type variables mentioned in the arg_tys
199 thinContext arg_tys ctxt
200 = filter in_arg_tys ctxt
202 arg_tyvars = tyVarsOfTypes arg_tys
203 in_arg_tys (clas,tys) = not $ isEmptyVarSet $
204 tyVarsOfTypes tys `intersectVarSet` arg_tyvars
206 getBangStrictness (Banged _) = markedStrict
207 getBangStrictness (Unbanged _) = notMarkedStrict
208 getBangStrictness (Unpacked _) = markedUnboxed
213 %************************************************************************
215 \subsection{Generating constructor/selector bindings for data declarations}
217 %************************************************************************
220 mkImplicitDataBinds :: Module -> [TyCon] -> TcM ([Id], TcMonoBinds)
221 mkImplicitDataBinds this_mod [] = returnTc ([], EmptyMonoBinds)
222 mkImplicitDataBinds this_mod (tycon : tycons)
223 | isSynTyCon tycon = mkImplicitDataBinds this_mod tycons
224 | otherwise = mkImplicitDataBinds_one this_mod tycon `thenTc` \ (ids1, b1) ->
225 mkImplicitDataBinds this_mod tycons `thenTc` \ (ids2, b2) ->
226 returnTc (ids1++ids2, b1 `AndMonoBinds` b2)
228 mkImplicitDataBinds_one this_mod tycon
229 = mapTc (mkRecordSelector tycon) groups `thenTc` \ sel_ids ->
231 unf_ids = sel_ids ++ data_con_wrapper_ids ++ gen_ids
232 all_ids = map dataConId data_cons ++ unf_ids
234 -- For the locally-defined things
235 -- we need to turn the unfoldings inside the selector Ids into bindings,
236 -- and build bindigns for the constructor wrappers
237 binds | isFrom this_mod tycon = idsToMonoBinds unf_ids
238 | otherwise = EmptyMonoBinds
240 returnTc (all_ids, binds)
242 data_cons = tyConDataConsIfAvailable tycon
243 -- Abstract types mean we don't bring the
244 -- data cons into scope, which should be fine
245 gen_ids = tyConGenIds tycon
246 data_con_wrapper_ids = map dataConWrapId data_cons
248 fields = [ (con, field) | con <- data_cons,
249 field <- dataConFieldLabels con
252 -- groups is list of fields that share a common name
253 groups = equivClasses cmp_name fields
254 cmp_name (_, field1) (_, field2)
255 = fieldLabelName field1 `compare` fieldLabelName field2
259 mkRecordSelector tycon fields@((first_con, first_field_label) : other_fields)
260 -- These fields all have the same name, but are from
261 -- different constructors in the data type
262 -- Check that all the fields in the group have the same type
263 -- This check assumes that all the constructors of a given
264 -- data type use the same type variables
265 = checkTc (all (== field_ty) other_tys)
266 (fieldTypeMisMatch field_name) `thenTc_`
267 tcLookupGlobalId unpackCStringName `thenTc` \ unpack_id ->
268 tcLookupGlobalId unpackCStringUtf8Name `thenTc` \ unpackUtf8_id ->
269 returnTc (mkRecordSelId tycon first_field_label unpack_id unpackUtf8_id)
271 field_ty = fieldLabelType first_field_label
272 field_name = fieldLabelName first_field_label
273 other_tys = [fieldLabelType fl | (_, fl) <- other_fields]
280 fieldTypeMisMatch field_name
281 = sep [ptext SLIT("Declared types differ for field"), quotes (ppr field_name)]
284 = ptext SLIT("Can't combine named fields with locally-quantified type variables")
286 (ptext SLIT("In the declaration of data constructor") <+> ppr name)