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
95 kc_field (_, bty) = kc_bty bty
99 %************************************************************************
101 \subsection{Type checking}
103 %************************************************************************
106 tcTyDecl :: RecFlag -> RenamedTyClDecl -> TcM s TyCon
108 tcTyDecl is_rec (TySynonym tycon_name tyvar_names rhs src_loc)
109 = tcLookupTy tycon_name `thenNF_Tc` \ (tycon_kind, Just arity, _) ->
110 tcExtendTopTyVarScope tycon_kind tyvar_names $ \ tyvars _ ->
111 tcHsTopType rhs `thenTc` \ rhs_ty ->
113 -- Construct the tycon
114 tycon = mkSynTyCon tycon_name tycon_kind arity tyvars rhs_ty
119 tcTyDecl is_rec (TyData data_or_new context tycon_name tyvar_names con_decls derivings pragmas src_loc)
120 = -- Lookup the pieces
121 tcLookupTy tycon_name `thenNF_Tc` \ (tycon_kind, _, ATyCon rec_tycon) ->
122 tcExtendTopTyVarScope tycon_kind tyvar_names $ \ tyvars _ ->
124 -- Typecheck the pieces
125 tcContext context `thenTc` \ ctxt ->
126 mapTc (tcConDecl rec_tycon tyvars ctxt) con_decls `thenTc` \ data_cons ->
127 tc_derivs derivings `thenTc` \ derived_classes ->
130 -- Construct the tycon
131 real_data_or_new = case data_or_new of
133 DataType | all isNullaryDataCon data_cons -> EnumType
134 | otherwise -> DataType
136 tycon = mkAlgTyCon tycon_name tycon_kind tyvars ctxt
139 Nothing -- Not a dictionary
140 real_data_or_new is_rec
144 tc_derivs Nothing = returnTc []
145 tc_derivs (Just ds) = mapTc tc_deriv ds
147 tc_deriv name = tcLookupTy name `thenTc` \ (_, _, AClass clas) ->
152 %************************************************************************
154 \subsection{Type check constructors}
156 %************************************************************************
159 tcConDecl :: TyCon -> [TyVar] -> ThetaType -> RenamedConDecl -> TcM s DataCon
161 tcConDecl tycon tyvars ctxt (ConDecl name ex_tvs ex_ctxt details src_loc)
162 = tcAddSrcLoc src_loc $
163 tcExtendTyVarScope ex_tvs $ \ ex_tyvars ->
164 tcContext ex_ctxt `thenTc` \ ex_theta ->
165 tc_con_decl_help tycon tyvars ctxt name ex_tyvars ex_theta details
167 tc_con_decl_help tycon tyvars ctxt name ex_tyvars ex_theta details
169 VanillaCon btys -> tc_datacon btys
170 InfixCon bty1 bty2 -> tc_datacon [bty1,bty2]
171 NewCon ty mb_f -> tc_newcon ty mb_f
172 RecCon fields -> tc_rec_con fields
176 arg_stricts = map get_strictness btys
177 tys = map get_pty btys
179 mapTc tcHsTopType tys `thenTc` \ arg_tys ->
180 mk_data_con arg_stricts arg_tys []
183 = tcHsTopBoxedType ty `thenTc` \ arg_ty ->
184 -- can't allow an unboxed type here, because we're effectively
185 -- going to remove the constructor while coercing it to a boxed type.
190 Just f -> [mkFieldLabel (getName f) arg_ty (head allFieldLabelTags)]
192 mk_data_con [NotMarkedStrict] [arg_ty] field_label
195 = checkTc (null ex_tyvars) (exRecConErr name) `thenTc_`
196 mapTc tc_field fields `thenTc` \ field_label_infos_s ->
198 field_label_infos = concat field_label_infos_s
199 arg_stricts = [strict | (_, _, strict) <- field_label_infos]
200 arg_tys = [ty | (_, ty, _) <- field_label_infos]
202 field_labels = [ mkFieldLabel (getName name) ty tag
203 | ((name, ty, _), tag) <- field_label_infos `zip` allFieldLabelTags ]
205 mk_data_con arg_stricts arg_tys field_labels
207 tc_field (field_label_names, bty)
208 = tcHsTopType (get_pty bty) `thenTc` \ field_ty ->
209 returnTc [(name, field_ty, get_strictness bty) | name <- field_label_names]
211 mk_data_con arg_stricts arg_tys fields
212 = -- Now we've checked all the field types we must
213 -- zonk the existential tyvars to finish the kind
214 -- inference on their kinds, and commit them to being
215 -- immutable type variables. (The top-level tyvars are
216 -- already fixed, by the preceding kind-inference pass.)
217 mapNF_Tc zonkTcTyVarToTyVar ex_tyvars `thenNF_Tc` \ ex_tyvars' ->
218 zonkTcThetaType ex_theta `thenNF_Tc` \ ex_theta' ->
220 data_con = mkDataCon name arg_stricts fields
221 tyvars (thinContext arg_tys ctxt)
225 data_con_id = mkDataConId data_con
229 -- The context for a data constructor should be limited to
230 -- the type variables mentioned in the arg_tys
231 thinContext arg_tys ctxt
232 = filter in_arg_tys ctxt
234 arg_tyvars = tyVarsOfTypes arg_tys
235 in_arg_tys (clas,tys) = not $ isEmptyVarSet $
236 tyVarsOfTypes tys `intersectVarSet` arg_tyvars
238 get_strictness (Banged _) = MarkedStrict
239 get_strictness (Unbanged _) = NotMarkedStrict
241 get_pty (Banged ty) = ty
242 get_pty (Unbanged ty) = ty
247 %************************************************************************
249 \subsection{Generating constructor/selector bindings for data declarations}
251 %************************************************************************
254 mkDataBinds :: [TyCon] -> TcM s ([Id], TcMonoBinds)
255 mkDataBinds [] = returnTc ([], EmptyMonoBinds)
256 mkDataBinds (tycon : tycons)
257 | isSynTyCon tycon = mkDataBinds tycons
258 | otherwise = mkDataBinds_one tycon `thenTc` \ (ids1, b1) ->
259 mkDataBinds tycons `thenTc` \ (ids2, b2) ->
260 returnTc (ids1++ids2, b1 `AndMonoBinds` b2)
262 mkDataBinds_one tycon
263 = mapTc (mkRecordSelector tycon) groups `thenTc` \ sel_ids ->
265 data_ids = map dataConId data_cons ++ sel_ids
267 -- For the locally-defined things
268 -- we need to turn the unfoldings inside the Ids into bindings,
269 binds = [ CoreMonoBind data_id (getUnfoldingTemplate (getIdUnfolding data_id))
270 | data_id <- data_ids, isLocallyDefined data_id
273 returnTc (data_ids, andMonoBindList binds)
275 data_cons = tyConDataCons tycon
276 fields = [ (con, field) | con <- data_cons,
277 field <- dataConFieldLabels con
280 -- groups is list of fields that share a common name
281 groups = equivClasses cmp_name fields
282 cmp_name (_, field1) (_, field2)
283 = fieldLabelName field1 `compare` fieldLabelName field2
287 mkRecordSelector tycon fields@((first_con, first_field_label) : other_fields)
288 -- These fields all have the same name, but are from
289 -- different constructors in the data type
290 -- Check that all the fields in the group have the same type
291 -- This check assumes that all the constructors of a given
292 -- data type use the same type variables
293 = checkTc (all (== field_ty) other_tys)
294 (fieldTypeMisMatch field_name) `thenTc_`
297 field_ty = fieldLabelType first_field_label
298 field_name = fieldLabelName first_field_label
299 other_tys = [fieldLabelType fl | (_, fl) <- other_fields]
300 (tyvars, _, _, _, _, _) = dataConSig first_con
301 data_ty = mkTyConApp tycon (mkTyVarTys tyvars)
302 -- tyvars of first_con may be free in field_ty
303 -- Now build the selector
306 selector_ty = mkForAllTys tyvars $
312 | isNewTyCon tycon = mkNewTySelId first_field_label selector_ty
313 | otherwise = mkRecordSelId first_field_label selector_ty
320 fieldTypeMisMatch field_name
321 = sep [ptext SLIT("Declared types differ for field"), quotes (ppr field_name)]
324 = ptext SLIT("Can't combine named fields with locally-quantified type variables")
326 (ptext SLIT("In the declaration of data constructor") <+> ppr name)