2 % (c) The AQUA Project, Glasgow University, 1996
4 \section[TcTyDecls]{Typecheck type declarations}
7 #include "HsVersions.h"
17 import HsSyn ( TyDecl(..), ConDecl(..), BangType(..), HsExpr(..),
18 Match(..), GRHSsAndBinds(..), GRHS(..), OutPat(..),
19 HsBinds(..), HsLit, Stmt, Qualifier, ArithSeqInfo,
20 PolyType, Fake, InPat,
21 Bind(..), MonoBinds(..), Sig,
23 import RnHsSyn ( RenamedTyDecl(..), RenamedConDecl(..),
24 RnName{-instance Outputable-}
26 import TcHsSyn ( mkHsTyLam, mkHsDictLam, tcIdType,
27 TcHsBinds(..), TcIdOcc(..)
29 import Inst ( newDicts, InstOrigin(..), Inst )
30 import TcMonoType ( tcMonoTypeKind, tcMonoType, tcPolyType, tcContext )
31 import TcSimplify ( tcSimplifyThetas )
32 import TcType ( tcInstTyVars, tcInstType, tcInstId )
33 import TcEnv ( tcLookupTyCon, tcLookupTyVar, tcLookupClass,
34 newLocalId, newLocalIds, tcLookupClassByKey
36 import TcMonad hiding ( rnMtoTcM )
37 import TcKind ( TcKind, unifyKind, mkTcArrowKind, mkTcTypeKind )
39 import PprType ( GenClass, GenType{-instance Outputable-} )
40 import Class ( GenClass{-instance Eq-}, classInstEnv )
41 import Id ( mkDataCon, dataConSig, mkRecordSelId, idType,
42 dataConFieldLabels, dataConStrictMarks,
44 GenId{-instance NamedThing-}
47 import Kind ( Kind, mkArrowKind, mkBoxedTypeKind )
48 import SpecEnv ( SpecEnv(..), nullSpecEnv )
49 import Name ( nameSrcLoc, isLocallyDefinedName, getSrcLoc,
52 import Outputable ( Outputable(..), interpp'SP )
54 import TyCon ( TyCon, NewOrData(..), mkSynTyCon, mkDataTyCon, isDataTyCon,
55 isNewTyCon, isSynTyCon, tyConDataCons
57 import Type ( GenType, -- instances
58 typeKind, getTyVar, tyVarsOfTypes, eqTy, splitSigmaTy,
59 applyTyCon, mkTyVarTys, mkForAllTys, mkFunTy,
60 splitFunTy, mkTyVarTy, getTyVar_maybe
62 import PprType ( GenTyVar{-instance Outputable-}{-ToDo:possibly rm-} )
63 import TyVar ( tyVarKind, elementOfTyVarSet, GenTyVar{-instance Eq-} )
64 import Unique ( Unique {- instance Eq -}, evalClassKey )
65 import UniqSet ( emptyUniqSet, mkUniqSet, uniqSetToList, unionManyUniqSets, UniqSet(..) )
66 import Util ( equivClasses, zipEqual, nOfThem, panic, assertPanic )
70 tcTyDecl :: RenamedTyDecl -> TcM s TyCon
77 tcTyDecl (TySynonym tycon_name tyvar_names rhs src_loc)
78 = tcAddSrcLoc src_loc $
79 tcAddErrCtxt (tySynCtxt tycon_name) $
82 tcLookupTyCon tycon_name `thenNF_Tc` \ (tycon_kind, _, rec_tycon) ->
83 mapAndUnzipNF_Tc tcLookupTyVar tyvar_names `thenNF_Tc` \ (tyvar_kinds, rec_tyvars) ->
86 tcMonoTypeKind rhs `thenTc` \ (rhs_kind, rhs_ty) ->
88 -- Unify tycon kind with (k1->...->kn->rhs)
90 (foldr mkTcArrowKind rhs_kind tyvar_kinds)
93 -- Getting the TyCon's kind is a bit of a nuisance. We can't use the tycon_kind,
94 -- because that's a TcKind and may not yet be fully unified with other kinds.
95 -- We could have augmented the tycon environment with a knot-tied kind,
96 -- but the simplest thing to do seems to be to get the Kind by (lazily)
97 -- looking at the tyvars and rhs_ty.
98 result_kind, final_tycon_kind :: Kind -- NB not TcKind!
99 result_kind = typeKind rhs_ty
100 final_tycon_kind = foldr (mkArrowKind . tyVarKind) result_kind rec_tyvars
102 -- Construct the tycon
103 tycon = mkSynTyCon (getName tycon_name)
112 Algebraic data and newtype decls
113 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
116 tcTyDecl (TyData context tycon_name tyvar_names con_decls derivings pragmas src_loc)
117 = tcTyDataOrNew DataType context tycon_name tyvar_names con_decls derivings pragmas src_loc
119 tcTyDecl (TyNew context tycon_name tyvar_names con_decl derivings pragmas src_loc)
120 = tcTyDataOrNew NewType context tycon_name tyvar_names con_decl derivings pragmas src_loc
123 tcTyDataOrNew data_or_new context tycon_name tyvar_names con_decls derivings pragmas src_loc
124 = tcAddSrcLoc src_loc $
125 tcAddErrCtxt (tyDataCtxt tycon_name) $
128 tcLookupTyCon tycon_name `thenNF_Tc` \ (tycon_kind, _, rec_tycon) ->
129 mapAndUnzipNF_Tc tcLookupTyVar tyvar_names `thenNF_Tc` \ (tyvar_kinds, rec_tyvars) ->
130 tc_derivs derivings `thenNF_Tc` \ derived_classes ->
132 -- Typecheck the context
133 tcContext context `thenTc` \ ctxt ->
135 -- Unify tycon kind with (k1->...->kn->Type)
137 (foldr mkTcArrowKind mkTcTypeKind tyvar_kinds)
141 mapTc (tcConDecl rec_tycon rec_tyvars ctxt) con_decls
142 `thenTc` \ con_ids ->
144 -- Construct the tycon
145 final_tycon_kind :: Kind -- NB not TcKind!
146 final_tycon_kind = foldr (mkArrowKind . tyVarKind) mkBoxedTypeKind rec_tyvars
148 tycon = mkDataTyCon (getName tycon_name)
158 tc_derivs Nothing = returnNF_Tc []
159 tc_derivs (Just ds) = mapNF_Tc tc_deriv ds
162 = tcLookupClass name `thenNF_Tc` \ (_, clas) ->
166 Generating constructor/selector bindings for data declarations
167 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
170 mkDataBinds :: [TyCon] -> TcM s ([Id], TcHsBinds s)
171 mkDataBinds [] = returnTc ([], EmptyBinds)
172 mkDataBinds (tycon : tycons)
173 | isSynTyCon tycon = mkDataBinds tycons
174 | otherwise = mkDataBinds_one tycon `thenTc` \ (ids1, b1) ->
175 mkDataBinds tycons `thenTc` \ (ids2, b2) ->
176 returnTc (ids1++ids2, b1 `ThenBinds` b2)
178 mkDataBinds_one tycon
179 = ASSERT( isDataTyCon tycon || isNewTyCon tycon )
180 mapAndUnzipTc mkConstructor data_cons `thenTc` \ (con_ids, con_binds) ->
181 mapAndUnzipTc (mkRecordSelector tycon) groups `thenTc` \ (sel_ids, sel_binds) ->
182 returnTc (con_ids ++ sel_ids,
183 SingleBind $ NonRecBind $
185 (foldr AndMonoBinds EmptyMonoBinds sel_binds)
189 data_cons = tyConDataCons tycon
190 fields = [ (con, field) | con <- data_cons,
191 field <- dataConFieldLabels con
194 -- groups is list of fields that share a common name
195 groups = equivClasses cmp_name fields
196 cmp_name (_, field1) (_, field2)
197 = fieldLabelName field1 `cmp` fieldLabelName field2
200 We're going to build a constructor that looks like:
202 data (Data a, C b) => T a b = T1 !a !Int b
205 \d1::Data a, d2::C b ->
206 \p q r -> case p of { p ->
208 HsCon T1 [a,b] [p,q,r]}}
212 * d2 is thrown away --- a context in a data decl is used to make sure
213 one *could* construct dictionaries at the site the constructor
214 is used, but the dictionary isn't actually used.
216 * We have to check that we can construct Data dictionaries for
217 the types a and Int. Once we've done that we can throw d1 away too.
219 * We use (case p of ...) to evaluate p, rather than "seq" because
220 all that matters is that the arguments are evaluated. "seq" is
221 very careful to preserve evaluation order, which we don't need
226 | not (isLocallyDefinedName (getName con_id))
227 = returnTc (con_id, EmptyMonoBinds)
229 | otherwise -- It is locally defined
230 = tcInstId con_id `thenNF_Tc` \ (tc_tyvars, tc_theta, tc_tau) ->
231 newDicts DataDeclOrigin tc_theta `thenNF_Tc` \ (_, dicts) ->
233 (tc_arg_tys, tc_result_ty) = splitFunTy tc_tau
234 n_args = length tc_arg_tys
236 newLocalIds (nOfThem n_args SLIT("con")) tc_arg_tys `thenNF_Tc` \ args ->
238 -- Check that all the types of all the strict arguments are in Eval
239 tcLookupClassByKey evalClassKey `thenNF_Tc` \ eval_clas ->
241 (_,theta,tau) = splitSigmaTy (idType con_id)
242 (arg_tys, _) = splitFunTy tau
243 strict_marks = dataConStrictMarks con_id
244 eval_theta = [ (eval_clas,arg_ty)
245 | (arg_ty, MarkedStrict) <- zipEqual "strict_args"
249 tcSimplifyThetas classInstEnv theta eval_theta `thenTc` \ eval_theta' ->
250 checkTc (null eval_theta')
251 (missingEvalErr con_id eval_theta') `thenTc_`
253 -- Build the data constructor
255 con_rhs = mkHsTyLam tc_tyvars $
258 mk_case (zipEqual "strict_args" args strict_marks) $
259 HsCon con_id (mkTyVarTys tc_tyvars) (map HsVar args)
261 mk_pat_match [] body = body
262 mk_pat_match (arg:args) body = HsLam $
263 PatMatch (VarPat arg) $
264 SimpleMatch (mk_pat_match args body)
266 mk_case [] body = body
267 mk_case ((arg,MarkedStrict):args) body = HsCase (HsVar arg)
268 [PatMatch (VarPat arg) $
269 SimpleMatch (mk_case args body)]
271 mk_case (_:args) body = mk_case args body
273 src_loc = nameSrcLoc (getName con_id)
276 returnTc (con_id, VarMonoBind (RealId con_id) con_rhs)
279 We're going to build a record selector that looks like this:
281 data T a b c = T1 { op :: a, ...}
285 sel :: forall a b c. T a b c -> a
286 sel = /\ a b c -> \ T1 { sel = x } -> x
289 Note that the selector Id itself is used as the field
290 label; it has to be an Id, you see!
293 mkRecordSelector tycon fields@((first_con, first_field_label) : other_fields)
295 field_ty = fieldLabelType first_field_label
296 field_name = fieldLabelName first_field_label
297 other_tys = [fieldLabelType fl | (_, fl) <- other_fields]
298 (tyvars, _, _, _) = dataConSig first_con
299 data_ty = applyTyCon tycon (mkTyVarTys tyvars)
300 -- tyvars of first_con may be free in field_ty
303 -- Check that all the fields in the group have the same type
304 -- This check assumes that all the constructors of a given
305 -- data type use the same type variables
306 checkTc (all (eqTy field_ty) other_tys)
307 (fieldTypeMisMatch field_name) `thenTc_`
309 -- Create an Id for the field itself
310 tcInstTyVars tyvars `thenNF_Tc` \ (tyvars', tyvar_tys, tenv) ->
311 tcInstType tenv field_ty `thenNF_Tc` \ field_ty' ->
313 data_ty' = applyTyCon tycon tyvar_tys
315 newLocalId SLIT("x") field_ty' `thenNF_Tc` \ field_id ->
316 newLocalId SLIT("r") data_ty' `thenNF_Tc` \ record_id ->
318 -- Now build the selector
321 selector_ty = mkForAllTys tyvars $
326 selector_id = mkRecordSelId first_field_label selector_ty
328 -- HsSyn is dreadfully verbose for defining the selector!
329 selector_rhs = mkHsTyLam tyvars' $
331 PatMatch (VarPat record_id) $
335 selector_body = HsCase (HsVar record_id) (map mk_match fields) (getSrcLoc tycon)
337 mk_match (con_id, field_label)
338 = PatMatch (RecPat con_id data_ty' [(selector_id, VarPat field_id, False)]) $
342 returnTc (selector_id, if isLocallyDefinedName (getName tycon)
343 then VarMonoBind (RealId selector_id) selector_rhs
350 tcConDecl :: TyCon -> [TyVar] -> [(Class,Type)] -> RenamedConDecl -> TcM s Id
352 tcConDecl tycon tyvars ctxt (ConDecl name btys src_loc)
353 = tcDataCon tycon tyvars ctxt name btys src_loc
355 tcConDecl tycon tyvars ctxt (ConOpDecl bty1 op bty2 src_loc)
356 = tcDataCon tycon tyvars ctxt op [bty1,bty2] src_loc
358 tcConDecl tycon tyvars ctxt (NewConDecl name ty src_loc)
359 = tcAddSrcLoc src_loc $
360 tcMonoType ty `thenTc` \ arg_ty ->
362 data_con = mkDataCon (getName name)
364 [{- No labelled fields -}]
373 tcConDecl tycon tyvars ctxt (RecConDecl name fields src_loc)
374 = tcAddSrcLoc src_loc $
375 mapTc tcField fields `thenTc` \ field_label_infos_s ->
377 field_label_infos = concat field_label_infos_s
378 stricts = [strict | (_, _, strict) <- field_label_infos]
379 arg_tys = [ty | (_, ty, _) <- field_label_infos]
381 field_labels = [ mkFieldLabel (getName name) ty tag
382 | ((name, ty, _), tag) <- field_label_infos `zip` allFieldLabelTags ]
384 data_con = mkDataCon (getName name)
388 (thinContext arg_tys ctxt)
395 tcField (field_label_names, bty)
396 = tcPolyType (get_pty bty) `thenTc` \ field_ty ->
397 returnTc [(name, field_ty, get_strictness bty) | name <- field_label_names]
399 tcDataCon tycon tyvars ctxt name btys src_loc
400 = tcAddSrcLoc src_loc $
402 stricts = map get_strictness btys
403 tys = map get_pty btys
405 mapTc tcPolyType tys `thenTc` \ arg_tys ->
407 data_con = mkDataCon (getName name)
409 [{- No field labels -}]
411 (thinContext arg_tys ctxt)
418 -- The context for a data constructor should be limited to
419 -- the type variables mentioned in the arg_tys
420 thinContext arg_tys ctxt
421 = filter in_arg_tys ctxt
423 arg_tyvars = tyVarsOfTypes arg_tys
424 in_arg_tys (clas,ty) = getTyVar "tcDataCon" ty `elementOfTyVarSet` arg_tyvars
426 get_strictness (Banged _) = MarkedStrict
427 get_strictness (Unbanged _) = NotMarkedStrict
429 get_pty (Banged ty) = ty
430 get_pty (Unbanged ty) = ty
438 tySynCtxt tycon_name sty
439 = ppCat [ppStr "In the type declaration for", ppr sty tycon_name]
441 tyDataCtxt tycon_name sty
442 = ppCat [ppStr "In the data declaration for", ppr sty tycon_name]
444 tyNewCtxt tycon_name sty
445 = ppCat [ppStr "In the newtype declaration for", ppr sty tycon_name]
447 fieldTypeMisMatch field_name sty
448 = ppSep [ppStr "Declared types differ for field", ppr sty field_name]
450 missingEvalErr con eval_theta sty
451 = ppCat [ppStr "Missing Eval context for constructor",
452 ppQuote (ppr sty con),
453 ppStr ":", ppr sty eval_theta]