2 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1996
4 \section[TcModule]{Typechecking a whole module}
13 #include "HsVersions.h"
15 import CmdLineOpts ( opt_D_dump_tc, opt_D_dump_deriv )
16 import HsSyn ( HsModule(..), HsBinds(..), MonoBinds(..), HsDecl(..) )
17 import RnHsSyn ( RenamedHsModule, RenamedFixityDecl(..) )
18 import TcHsSyn ( TypecheckedHsBinds, TypecheckedHsExpr,
19 TypecheckedDictBinds, TcMonoBinds,
24 import Inst ( Inst, emptyLIE, plusLIE )
25 import TcBinds ( tcTopBindsAndThen )
26 import TcClassDcl ( tcClassDecls2 )
27 import TcDefaults ( tcDefaults )
28 import TcEnv ( TcIdOcc(..), tcExtendGlobalValEnv, tcExtendTyConEnv, getEnv_LocalIds,
29 getEnv_TyCons, getEnv_Classes, tcLookupLocalValue,
30 tcLookupLocalValueByKey, tcLookupTyCon,
31 tcLookupGlobalValueByKeyMaybe )
32 import TcExpr ( tcId )
33 import TcIfaceSig ( tcInterfaceSigs )
34 import TcInstDcls ( tcInstDecls1, tcInstDecls2 )
35 import TcInstUtil ( buildInstanceEnvs, classDataCon, InstInfo )
36 import TcSimplify ( tcSimplifyTop )
37 import TcTyClsDecls ( tcTyAndClassDecls1 )
38 import TcTyDecls ( mkDataBinds )
39 import TcType ( TcType, tcInstType )
40 import TcKind ( TcKind, kindToTcKind )
42 import RnMonad ( RnNameSupply(..) )
43 import Bag ( isEmptyBag )
44 import ErrUtils ( WarnMsg, ErrMsg,
45 pprBagOfErrors, dumpIfSet, ghcExit
47 import Id ( idType, GenId, IdEnv, nullIdEnv )
48 import Maybes ( catMaybes, MaybeErr(..) )
49 import Name ( Name, isLocallyDefined, pprModule, NamedThing(..) )
50 import TyCon ( TyCon, isSynTyCon, tyConKind )
51 import Class ( Class, classSelIds, classTyCon )
52 import Type ( mkTyConApp, mkSynTy, Type )
53 import TyVar ( emptyTyVarEnv )
54 import TysWiredIn ( unitTy )
55 import PrelMods ( gHC_MAIN, mAIN )
56 import PrelInfo ( main_NAME, ioTyCon_NAME )
57 import Unify ( unifyTauTy )
58 import UniqFM ( lookupUFM_Directly, lookupWithDefaultUFM_Directly,
60 import Unique ( Unique )
61 import UniqSupply ( UniqSupply )
63 import Bag ( Bag, isEmptyBag )
64 import FiniteMap ( emptyFM, FiniteMap )
68 Outside-world interface:
71 -- Convenient type synonyms first:
73 = (TypecheckedMonoBinds,
75 Bag InstInfo, -- Instance declaration information
78 type TcDDumpDeriv = SDoc
85 -> IO (Maybe TcResults)
87 typecheckModule us rn_name_supply mod
89 (maybe_result, warns, errs) = initTc us (tcModule rn_name_supply mod)
94 dumpIfSet opt_D_dump_tc "Typechecked"
96 Just (binds, _, _, _, _) -> ppr binds
97 Nothing -> text "Typecheck failed") >>
99 dumpIfSet opt_D_dump_deriv "Derived instances"
100 (case maybe_result of
101 Just (_, _, _, _, dump_deriv) -> dump_deriv
104 return (if isEmptyBag errs then
110 | isEmptyBag errs = return ()
111 | otherwise = printErrs (pprBagOfErrors errs)
114 The internal monster:
116 tcModule :: RnNameSupply -- for renaming derivings
117 -> RenamedHsModule -- input
118 -> TcM s TcResults -- output
120 tcModule rn_name_supply
121 (HsModule mod_name verion exports imports fixities decls src_loc)
122 = tcAddSrcLoc src_loc $ -- record where we're starting
124 fixTc (\ ~(unf_env ,_) ->
125 -- unf_env is used for type-checking interface pragmas
126 -- which is done lazily [ie failure just drops the pragma
127 -- without having any global-failure effect].
129 -- unf_env is also used to get the pragam info for dfuns.
131 -- The knot for instance information. This isn't used at all
132 -- till we type-check value declarations
133 fixTc ( \ ~(rec_inst_mapper, _, _, _, _) ->
135 -- Type-check the type and class decls
136 -- trace "tcTyAndClassDecls:" $
137 tcTyAndClassDecls1 unf_env rec_inst_mapper decls `thenTc` \ env ->
140 -- Typecheck the instance decls, includes deriving
142 -- trace "tcInstDecls:" $
143 tcInstDecls1 unf_env decls mod_name rn_name_supply
144 ) `thenTc` \ (inst_info, deriv_binds, ddump_deriv) ->
147 buildInstanceEnvs inst_info `thenNF_Tc` \ inst_mapper ->
149 returnTc (inst_mapper, env, inst_info, deriv_binds, ddump_deriv)
151 -- End of inner fix loop
152 ) `thenTc` \ (_, env, inst_info, deriv_binds, ddump_deriv) ->
157 -- Default declarations
158 tcDefaults decls `thenTc` \ defaulting_tys ->
159 tcSetDefaultTys defaulting_tys $
161 -- Create any necessary record selector Ids and their bindings
162 -- "Necessary" includes data and newtype declarations
164 tycons = getEnv_TyCons env
165 classes = getEnv_Classes env
166 local_tycons = filter isLocallyDefined tycons
167 local_classes = filter isLocallyDefined classes
169 mkDataBinds tycons `thenTc` \ (data_ids, data_binds) ->
171 -- Extend the global value environment with
173 -- (b) record selectors
174 -- (c) class op selectors
175 -- (d) default-method ids
176 tcExtendGlobalValEnv data_ids $
177 tcExtendGlobalValEnv (concat (map classSelIds classes)) $
179 -- Extend the TyCon envt with the tycons corresponding to
180 -- the classes, and the global value environment with the
181 -- corresponding data cons.
182 -- They are mentioned in types in interface files.
183 tcExtendGlobalValEnv (map classDataCon classes) $
184 tcExtendTyConEnv [ (getName tycon, (kindToTcKind (tyConKind tycon), Nothing, tycon))
186 let tycon = classTyCon clas
189 -- Interface type signatures
190 -- We tie a knot so that the Ids read out of interfaces are in scope
191 -- when we read their pragmas.
192 -- What we rely on is that pragmas are typechecked lazily; if
193 -- any type errors are found (ie there's an inconsistency)
194 -- we silently discard the pragma
195 tcInterfaceSigs unf_env decls `thenTc` \ sig_ids ->
196 tcExtendGlobalValEnv sig_ids $
199 -- Value declarations next.
200 -- We also typecheck any extra binds that came out of the "deriving" process
201 -- trace "tcBinds:" $
203 (\ is_rec binds1 (binds2, thing) -> (binds1 `AndMonoBinds` binds2, thing))
204 (get_val_decls decls `ThenBinds` deriv_binds)
205 ( tcGetEnv `thenNF_Tc` \ env ->
206 returnTc ((EmptyMonoBinds, env), emptyLIE)
207 ) `thenTc` \ ((val_binds, final_env), lie_valdecls) ->
211 -- Second pass over class and instance declarations,
212 -- to compile the bindings themselves.
214 tcInstDecls2 inst_info `thenNF_Tc` \ (lie_instdecls, inst_binds) ->
215 tcClassDecls2 decls `thenNF_Tc` \ (lie_clasdecls, cls_binds) ->
219 -- Check that "main" has the right signature
220 tcCheckMainSig mod_name `thenTc_`
222 -- Deal with constant or ambiguous InstIds. How could
223 -- there be ambiguous ones? They can only arise if a
224 -- top-level decl falls under the monomorphism
225 -- restriction, and no subsequent decl instantiates its
226 -- type. (Usually, ambiguous type variables are resolved
227 -- during the generalisation step.)
230 lie_alldecls = lie_valdecls `plusLIE` lie_instdecls `plusLIE` lie_clasdecls
232 tcSimplifyTop lie_alldecls `thenTc` \ const_inst_binds ->
235 -- Backsubstitution. This must be done last.
236 -- Even tcCheckMainSig and tcSimplifyTop may do some unification.
238 all_binds = data_binds `AndMonoBinds`
239 val_binds `AndMonoBinds`
240 inst_binds `AndMonoBinds`
241 cls_binds `AndMonoBinds`
244 zonkTopBinds all_binds `thenNF_Tc` \ (all_binds', really_final_env) ->
246 returnTc (really_final_env,
247 (all_binds', local_tycons, local_classes, inst_info, ddump_deriv))
249 -- End of outer fix loop
250 ) `thenTc` \ (final_env, stuff) ->
253 get_val_decls decls = foldr ThenBinds EmptyBinds [binds | ValD binds <- decls]
258 tcCheckMainSig mod_name
260 = returnTc () -- A non-main module
263 = -- Check that main is defined
264 tcLookupTyCon ioTyCon_NAME `thenTc` \ (_,_,ioTyCon) ->
265 tcLookupLocalValue main_NAME `thenNF_Tc` \ maybe_main_id ->
266 case maybe_main_id of {
267 Nothing -> failWithTc noMainErr ;
270 -- Check that it has the right type (or a more general one)
272 expected_ty = mkTyConApp ioTyCon [unitTy]
274 tcInstType emptyTyVarEnv expected_ty `thenNF_Tc` \ expected_tau ->
275 tcId main_NAME `thenNF_Tc` \ (_, lie, main_tau) ->
276 tcSetErrCtxt mainTyCheckCtxt $
277 unifyTauTy expected_tau
279 checkTc (isEmptyBag lie) (mainTyMisMatch expected_ty (idType main_id))
284 = hsep [ptext SLIT("When checking that"), ppr main_NAME, ptext SLIT("has the required type")]
287 = hsep [ptext SLIT("Module"), quotes (pprModule mAIN),
288 ptext SLIT("must include a definition for"), quotes (ppr main_NAME)]
290 mainTyMisMatch :: Type -> TcType s -> ErrMsg
291 mainTyMisMatch expected actual
292 = hang (hsep [ppr main_NAME, ptext SLIT("has the wrong type")])
294 hsep [ptext SLIT("Expected:"), ppr expected],
295 hsep [ptext SLIT("Inferred:"), ppr actual]