2 % (c) The AQUA Project, Glasgow University, 1996-1998
4 \section[TcTyDecls]{Typecheck type declarations}
13 #include "HsVersions.h"
15 import HsSyn ( MonoBinds(..),
16 TyClDecl(..), ConDecl(..), ConDetails(..), BangType(..),
19 import RnHsSyn ( RenamedTyClDecl, RenamedConDecl )
20 import TcHsSyn ( TcMonoBinds )
21 import BasicTypes ( RecFlag(..), NewOrData(..), StrictnessMark(..) )
23 import TcMonoType ( tcExtendTopTyVarScope, tcExtendTyVarScope,
24 tcHsTypeKind, tcHsType, tcHsTopType, tcHsTopBoxedType,
27 import TcType ( zonkTcTyVarToTyVar, zonkTcThetaType )
28 import TcEnv ( tcLookupTy, TcTyThing(..) )
30 import TcUnify ( unifyKind )
32 import Class ( Class )
33 import DataCon ( DataCon, dataConSig, mkDataCon, isNullaryDataCon,
34 dataConFieldLabels, dataConId
36 import MkId ( mkDataConId, mkRecordSelId, mkNewTySelId )
37 import Id ( getIdUnfolding )
38 import CoreUnfold ( getUnfoldingTemplate )
40 import Var ( Id, TyVar )
41 import Name ( isLocallyDefined, OccName, NamedThing(..) )
43 import TyCon ( TyCon, mkSynTyCon, mkAlgTyCon, isAlgTyCon,
44 isSynTyCon, tyConDataCons, isNewTyCon
46 import Type ( getTyVar, tyVarsOfTypes,
47 mkTyConApp, mkTyVarTys, mkForAllTys, mkFunTy,
49 mkArrowKind, mkArrowKinds, boxedTypeKind,
50 isUnboxedType, Type, ThetaType
52 import Var ( tyVarKind )
53 import VarSet ( intersectVarSet, isEmptyVarSet )
54 import Util ( equivClasses )
57 %************************************************************************
59 \subsection{Kind checking}
61 %************************************************************************
64 kcTyDecl :: RenamedTyClDecl -> TcM s ()
66 kcTyDecl (TySynonym name tyvar_names rhs src_loc)
67 = tcLookupTy name `thenNF_Tc` \ (kind, _, _) ->
68 tcExtendTopTyVarScope kind tyvar_names $ \ _ result_kind ->
69 tcHsTypeKind rhs `thenTc` \ (rhs_kind, _) ->
70 unifyKind result_kind rhs_kind
72 kcTyDecl (TyData _ context tycon_name tyvar_names con_decls _ _ src_loc)
73 = tcLookupTy tycon_name `thenNF_Tc` \ (kind, _, _) ->
74 tcExtendTopTyVarScope kind tyvar_names $ \ result_kind _ ->
75 tcContext context `thenTc_`
76 mapTc kcConDecl con_decls `thenTc_`
79 kcConDecl (ConDecl _ ex_tvs ex_ctxt details loc)
81 tcExtendTyVarScope ex_tvs ( \ tyvars ->
82 tcContext ex_ctxt `thenTc_`
83 kc_con details `thenTc_`
87 kc_con (VanillaCon btys) = mapTc kc_bty btys `thenTc_` returnTc ()
88 kc_con (InfixCon bty1 bty2) = mapTc kc_bty [bty1,bty2] `thenTc_` returnTc ()
89 kc_con (NewCon ty _) = tcHsType ty `thenTc_` returnTc ()
90 kc_con (RecCon flds) = mapTc kc_field flds `thenTc_` returnTc ()
92 kc_bty (Banged ty) = tcHsType ty
93 kc_bty (Unbanged ty) = tcHsType ty
94 kc_bty (Unpacked ty) = tcHsType ty
96 kc_field (_, bty) = kc_bty bty
100 %************************************************************************
102 \subsection{Type checking}
104 %************************************************************************
107 tcTyDecl :: RecFlag -> RenamedTyClDecl -> TcM s TyCon
109 tcTyDecl is_rec (TySynonym tycon_name tyvar_names rhs src_loc)
110 = tcLookupTy tycon_name `thenNF_Tc` \ (tycon_kind, Just arity, _) ->
111 tcExtendTopTyVarScope tycon_kind tyvar_names $ \ tyvars _ ->
112 tcHsTopType rhs `thenTc` \ rhs_ty ->
114 -- Construct the tycon
115 tycon = mkSynTyCon tycon_name tycon_kind arity tyvars rhs_ty
120 tcTyDecl is_rec (TyData data_or_new context tycon_name tyvar_names con_decls derivings pragmas src_loc)
121 = -- Lookup the pieces
122 tcLookupTy tycon_name `thenNF_Tc` \ (tycon_kind, _, ATyCon rec_tycon) ->
123 tcExtendTopTyVarScope tycon_kind tyvar_names $ \ tyvars _ ->
125 -- Typecheck the pieces
126 tcContext context `thenTc` \ ctxt ->
127 mapTc (tcConDecl rec_tycon tyvars ctxt) con_decls `thenTc` \ data_cons ->
128 tc_derivs derivings `thenTc` \ derived_classes ->
131 -- Construct the tycon
132 real_data_or_new = case data_or_new of
134 DataType | all isNullaryDataCon data_cons -> EnumType
135 | otherwise -> DataType
137 tycon = mkAlgTyCon tycon_name tycon_kind tyvars ctxt
140 Nothing -- Not a dictionary
141 real_data_or_new is_rec
145 tc_derivs Nothing = returnTc []
146 tc_derivs (Just ds) = mapTc tc_deriv ds
148 tc_deriv name = tcLookupTy name `thenTc` \ (_, _, AClass clas) ->
153 %************************************************************************
155 \subsection{Type check constructors}
157 %************************************************************************
160 tcConDecl :: TyCon -> [TyVar] -> ThetaType -> RenamedConDecl -> TcM s DataCon
162 tcConDecl tycon tyvars ctxt (ConDecl name ex_tvs ex_ctxt details src_loc)
163 = tcAddSrcLoc src_loc $
164 tcExtendTyVarScope ex_tvs $ \ ex_tyvars ->
165 tcContext ex_ctxt `thenTc` \ ex_theta ->
166 tc_con_decl_help tycon tyvars ctxt name ex_tyvars ex_theta details
168 tc_con_decl_help tycon tyvars ctxt name ex_tyvars ex_theta details
170 VanillaCon btys -> tc_datacon btys
171 InfixCon bty1 bty2 -> tc_datacon [bty1,bty2]
172 NewCon ty mb_f -> tc_newcon ty mb_f
173 RecCon fields -> tc_rec_con fields
177 arg_stricts = map get_strictness btys
178 tys = map get_pty btys
180 mapTc tcHsTopType tys `thenTc` \ arg_tys ->
181 mk_data_con arg_stricts arg_tys []
184 = tcHsTopBoxedType ty `thenTc` \ arg_ty ->
185 -- can't allow an unboxed type here, because we're effectively
186 -- going to remove the constructor while coercing it to a boxed type.
191 Just f -> [mkFieldLabel (getName f) arg_ty (head allFieldLabelTags)]
193 mk_data_con [NotMarkedStrict] [arg_ty] field_label
196 = checkTc (null ex_tyvars) (exRecConErr name) `thenTc_`
197 mapTc tc_field fields `thenTc` \ field_label_infos_s ->
199 field_label_infos = concat field_label_infos_s
200 arg_stricts = [strict | (_, _, strict) <- field_label_infos]
201 arg_tys = [ty | (_, ty, _) <- field_label_infos]
203 field_labels = [ mkFieldLabel (getName name) ty tag
204 | ((name, ty, _), tag) <- field_label_infos `zip` allFieldLabelTags ]
206 mk_data_con arg_stricts arg_tys field_labels
208 tc_field (field_label_names, bty)
209 = tcHsTopType (get_pty bty) `thenTc` \ field_ty ->
210 returnTc [(name, field_ty, get_strictness bty) | name <- field_label_names]
212 mk_data_con arg_stricts arg_tys fields
213 = -- Now we've checked all the field types we must
214 -- zonk the existential tyvars to finish the kind
215 -- inference on their kinds, and commit them to being
216 -- immutable type variables. (The top-level tyvars are
217 -- already fixed, by the preceding kind-inference pass.)
218 mapNF_Tc zonkTcTyVarToTyVar ex_tyvars `thenNF_Tc` \ ex_tyvars' ->
219 zonkTcThetaType ex_theta `thenNF_Tc` \ ex_theta' ->
221 data_con = mkDataCon name arg_stricts fields
222 tyvars (thinContext arg_tys ctxt)
226 data_con_id = mkDataConId data_con
230 -- The context for a data constructor should be limited to
231 -- the type variables mentioned in the arg_tys
232 thinContext arg_tys ctxt
233 = filter in_arg_tys ctxt
235 arg_tyvars = tyVarsOfTypes arg_tys
236 in_arg_tys (clas,tys) = not $ isEmptyVarSet $
237 tyVarsOfTypes tys `intersectVarSet` arg_tyvars
239 get_strictness (Banged _) = MarkedStrict
240 get_strictness (Unbanged _) = NotMarkedStrict
241 get_strictness (Unpacked _) = MarkedUnboxed bot bot
242 where bot = error "get_strictness"
244 get_pty (Banged ty) = ty
245 get_pty (Unbanged ty) = ty
246 get_pty (Unpacked ty) = ty
251 %************************************************************************
253 \subsection{Generating constructor/selector bindings for data declarations}
255 %************************************************************************
258 mkDataBinds :: [TyCon] -> TcM s ([Id], TcMonoBinds)
259 mkDataBinds [] = returnTc ([], EmptyMonoBinds)
260 mkDataBinds (tycon : tycons)
261 | isSynTyCon tycon = mkDataBinds tycons
262 | otherwise = mkDataBinds_one tycon `thenTc` \ (ids1, b1) ->
263 mkDataBinds tycons `thenTc` \ (ids2, b2) ->
264 returnTc (ids1++ids2, b1 `AndMonoBinds` b2)
266 mkDataBinds_one tycon
267 = mapTc (mkRecordSelector tycon) groups `thenTc` \ sel_ids ->
269 data_ids = map dataConId data_cons ++ sel_ids
271 -- For the locally-defined things
272 -- we need to turn the unfoldings inside the Ids into bindings,
273 binds = [ CoreMonoBind data_id (getUnfoldingTemplate (getIdUnfolding data_id))
274 | data_id <- data_ids, isLocallyDefined data_id
277 returnTc (data_ids, andMonoBindList binds)
279 data_cons = tyConDataCons tycon
280 fields = [ (con, field) | con <- data_cons,
281 field <- dataConFieldLabels con
284 -- groups is list of fields that share a common name
285 groups = equivClasses cmp_name fields
286 cmp_name (_, field1) (_, field2)
287 = fieldLabelName field1 `compare` fieldLabelName field2
291 mkRecordSelector tycon fields@((first_con, first_field_label) : other_fields)
292 -- These fields all have the same name, but are from
293 -- different constructors in the data type
294 -- Check that all the fields in the group have the same type
295 -- This check assumes that all the constructors of a given
296 -- data type use the same type variables
297 = checkTc (all (== field_ty) other_tys)
298 (fieldTypeMisMatch field_name) `thenTc_`
301 field_ty = fieldLabelType first_field_label
302 field_name = fieldLabelName first_field_label
303 other_tys = [fieldLabelType fl | (_, fl) <- other_fields]
304 (tyvars, _, _, _, _, _) = dataConSig first_con
305 data_ty = mkTyConApp tycon (mkTyVarTys tyvars)
306 -- tyvars of first_con may be free in field_ty
307 -- Now build the selector
310 selector_ty = mkForAllTys tyvars $
316 | isNewTyCon tycon = mkNewTySelId first_field_label selector_ty
317 | otherwise = mkRecordSelId first_field_label selector_ty
324 fieldTypeMisMatch field_name
325 = sep [ptext SLIT("Declared types differ for field"), quotes (ppr field_name)]
328 = ptext SLIT("Can't combine named fields with locally-quantified type variables")
330 (ptext SLIT("In the declaration of data constructor") <+> ppr name)