2 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
4 \section[TcModule]{Typechecking a whole module}
12 #include "HsVersions.h"
14 import CmdLineOpts ( opt_D_dump_tc )
15 import HsSyn ( HsModule(..), HsBinds(..), MonoBinds(..), HsDecl(..) )
16 import RnHsSyn ( RenamedHsModule )
17 import TcHsSyn ( TcMonoBinds, TypecheckedMonoBinds, zonkTopBinds,
18 TypecheckedForeignDecl, zonkForeignExports
22 import Inst ( Inst, emptyLIE, plusLIE )
23 import TcBinds ( tcTopBindsAndThen )
24 import TcClassDcl ( tcClassDecls2 )
25 import TcDefaults ( tcDefaults )
26 import TcEnv ( tcExtendGlobalValEnv, tcExtendTypeEnv,
27 getEnvTyCons, getEnvClasses, tcLookupValueMaybe,
28 explicitLookupValueByKey, tcSetValueEnv,
29 tcLookupTyCon, initEnv,
30 ValueEnv, TcTyThing(..)
32 import TcExpr ( tcId )
33 import TcForeign ( tcForeignImports, tcForeignExports )
34 import TcIfaceSig ( tcInterfaceSigs )
35 import TcInstDcls ( tcInstDecls1, tcInstDecls2 )
36 import TcInstUtil ( buildInstanceEnvs, classDataCon, InstInfo )
37 import TcSimplify ( tcSimplifyTop )
38 import TcTyClsDecls ( tcTyAndClassDecls )
39 import TcTyDecls ( mkDataBinds )
40 import TcType ( TcType, typeToTcType,
44 import RnMonad ( RnNameSupply )
45 import Bag ( isEmptyBag )
46 import ErrUtils ( ErrMsg,
47 pprBagOfErrors, dumpIfSet
49 import Id ( Id, idType )
50 import Name ( Name, nameUnique, isLocallyDefined, pprModule, NamedThing(..) )
51 import TyCon ( TyCon, tyConKind )
52 import DataCon ( dataConId )
53 import Class ( Class, classSelIds, classTyCon )
54 import Type ( mkTyConApp, Type )
55 import TysWiredIn ( unitTy )
56 import PrelMods ( mAIN )
57 import PrelInfo ( main_NAME, ioTyCon_NAME,
58 thinAirIdNames, setThinAirIds
60 import TcUnify ( unifyTauTy )
61 import Unique ( Unique )
62 import UniqSupply ( UniqSupply )
64 import Bag ( Bag, isEmptyBag )
70 Outside-world interface:
73 -- Convenient type synonyms first:
75 = (TypecheckedMonoBinds,
77 Bag InstInfo, -- Instance declaration information
78 [TypecheckedForeignDecl], -- foreign import & exports.
80 [Id] -- The thin-air Ids
88 -> IO (Maybe TcResults)
90 typecheckModule us rn_name_supply mod
91 = initTc us initEnv (tcModule rn_name_supply mod) >>= \ (maybe_result, warns, errs) ->
96 -- write the thin-air Id map
98 Just (_, _, _, _, _, _, thin_air_ids) -> setThinAirIds thin_air_ids
102 dumpIfSet opt_D_dump_tc "Typechecked"
103 (case maybe_result of
104 Just (binds, _, _, _, _, _, _) -> ppr binds
105 Nothing -> text "Typecheck failed") >>
107 return (if isEmptyBag errs then
113 | isEmptyBag errs = return ()
114 | otherwise = printErrs (pprBagOfErrors errs)
117 The internal monster:
119 tcModule :: RnNameSupply -- for renaming derivings
120 -> RenamedHsModule -- input
121 -> TcM s TcResults -- output
123 tcModule rn_name_supply
124 (HsModule mod_name verion exports imports decls src_loc)
125 = tcAddSrcLoc src_loc $ -- record where we're starting
127 fixTc (\ ~(unf_env ,_) ->
128 -- unf_env is used for type-checking interface pragmas
129 -- which is done lazily [ie failure just drops the pragma
130 -- without having any global-failure effect].
132 -- unf_env is also used to get the pragam info
133 -- for imported dfuns and default methods
135 -- The knot for instance information. This isn't used at all
136 -- till we type-check value declarations
137 fixTc ( \ ~(rec_inst_mapper, _, _, _) ->
139 -- Type-check the type and class decls
140 tcTyAndClassDecls unf_env rec_inst_mapper decls `thenTc` \ env ->
142 -- Typecheck the instance decls, includes deriving
144 tcInstDecls1 unf_env decls mod_name rn_name_supply
145 ) `thenTc` \ (inst_info, deriv_binds) ->
147 buildInstanceEnvs inst_info `thenNF_Tc` \ inst_mapper ->
149 returnTc (inst_mapper, env, inst_info, deriv_binds)
151 -- End of inner fix loop
152 ) `thenTc` \ (_, env, inst_info, deriv_binds) ->
156 -- Default declarations
157 tcDefaults decls `thenTc` \ defaulting_tys ->
158 tcSetDefaultTys defaulting_tys $
160 -- Create any necessary record selector Ids and their bindings
161 -- "Necessary" includes data and newtype declarations
162 -- We don't create bindings for dictionary constructors;
163 -- they are always fully applied, and the bindings are just there
164 -- to support partial applications
166 tycons = getEnvTyCons env
167 classes = getEnvClasses env
168 local_tycons = filter isLocallyDefined tycons
169 local_classes = filter isLocallyDefined classes
171 mkDataBinds tycons `thenTc` \ (data_ids, data_binds) ->
173 -- Extend the global value environment with
175 -- (b) record selectors
176 -- (c) class op selectors
177 -- (d) default-method ids... where? I can't see where these are
178 -- put into the envt, and I'm worried that the zonking phase
179 -- will find they aren't there and complain.
180 tcExtendGlobalValEnv data_ids $
181 tcExtendGlobalValEnv (concat (map classSelIds classes)) $
183 -- Extend the TyCon envt with the tycons corresponding to
184 -- the classes, and the global value environment with the
185 -- corresponding data cons.
186 -- They are mentioned in types in interface files.
187 tcExtendGlobalValEnv (map (dataConId . classDataCon) classes) $
188 tcExtendTypeEnv [ (getName tycon, (kindToTcKind (tyConKind tycon), Nothing, ATyCon tycon))
190 let tycon = classTyCon clas
193 -- Interface type signatures
194 -- We tie a knot so that the Ids read out of interfaces are in scope
195 -- when we read their pragmas.
196 -- What we rely on is that pragmas are typechecked lazily; if
197 -- any type errors are found (ie there's an inconsistency)
198 -- we silently discard the pragma
199 tcInterfaceSigs unf_env decls `thenTc` \ sig_ids ->
200 tcExtendGlobalValEnv sig_ids $
202 -- foreign import declarations next.
203 tcForeignImports decls `thenTc` \ (fo_ids, foi_decls) ->
204 tcExtendGlobalValEnv fo_ids $
206 -- Value declarations next.
207 -- We also typecheck any extra binds that came out of the "deriving" process
209 (\ is_rec binds1 (binds2, thing) -> (binds1 `AndMonoBinds` binds2, thing))
210 (get_val_decls decls `ThenBinds` deriv_binds)
211 ( tcGetEnv `thenNF_Tc` \ env ->
212 tcGetUnique `thenNF_Tc` \ uniq ->
213 returnTc ((EmptyMonoBinds, env), emptyLIE)
214 ) `thenTc` \ ((val_binds, final_env), lie_valdecls) ->
217 -- foreign export declarations next.
218 tcForeignExports decls `thenTc` \ (lie_fodecls, foe_binds, foe_decls) ->
220 -- Second pass over class and instance declarations,
221 -- to compile the bindings themselves.
222 tcInstDecls2 inst_info `thenNF_Tc` \ (lie_instdecls, inst_binds) ->
223 tcClassDecls2 decls `thenNF_Tc` \ (lie_clasdecls, cls_binds) ->
225 -- Check that "main" has the right signature
226 tcCheckMainSig mod_name `thenTc_`
228 -- Deal with constant or ambiguous InstIds. How could
229 -- there be ambiguous ones? They can only arise if a
230 -- top-level decl falls under the monomorphism
231 -- restriction, and no subsequent decl instantiates its
232 -- type. (Usually, ambiguous type variables are resolved
233 -- during the generalisation step.)
235 lie_alldecls = lie_valdecls `plusLIE`
236 lie_instdecls `plusLIE`
237 lie_clasdecls `plusLIE`
240 tcSimplifyTop lie_alldecls `thenTc` \ const_inst_binds ->
243 -- Backsubstitution. This must be done last.
244 -- Even tcCheckMainSig and tcSimplifyTop may do some unification.
246 all_binds = data_binds `AndMonoBinds`
247 val_binds `AndMonoBinds`
248 inst_binds `AndMonoBinds`
249 cls_binds `AndMonoBinds`
250 const_inst_binds `AndMonoBinds`
253 zonkTopBinds all_binds `thenNF_Tc` \ (all_binds', really_final_env) ->
254 tcSetValueEnv really_final_env $
255 zonkForeignExports foe_decls `thenNF_Tc` \ foe_decls' ->
258 thin_air_ids = map (explicitLookupValueByKey really_final_env . nameUnique) thinAirIdNames
259 -- When looking up the thin-air names we must use
260 -- a global env that includes the zonked locally-defined Ids too
261 -- Hence using really_final_env
263 returnTc (really_final_env,
264 (all_binds', local_tycons, local_classes, inst_info,
265 foi_decls ++ foe_decls',
270 -- End of outer fix loop
271 ) `thenTc` \ (final_env, stuff) ->
274 get_val_decls decls = foldr ThenBinds EmptyBinds [binds | ValD binds <- decls]
279 tcCheckMainSig mod_name
281 = returnTc () -- A non-main module
284 = -- Check that main is defined
285 tcLookupTyCon ioTyCon_NAME `thenTc` \ ioTyCon ->
286 tcLookupValueMaybe main_NAME `thenNF_Tc` \ maybe_main_id ->
287 case maybe_main_id of {
288 Nothing -> failWithTc noMainErr ;
291 -- Check that it has the right type (or a more general one)
293 expected_tau = typeToTcType (mkTyConApp ioTyCon [unitTy])
295 tcId main_NAME `thenNF_Tc` \ (_, lie, main_tau) ->
296 tcSetErrCtxt mainTyCheckCtxt $
297 unifyTauTy expected_tau
299 checkTc (isEmptyBag lie) (mainTyMisMatch expected_tau (idType main_id))
304 = hsep [ptext SLIT("When checking that"), ppr main_NAME, ptext SLIT("has the required type")]
307 = hsep [ptext SLIT("Module"), quotes (pprModule mAIN),
308 ptext SLIT("must include a definition for"), quotes (ppr main_NAME)]
310 mainTyMisMatch :: TcType -> TcType -> ErrMsg
311 mainTyMisMatch expected actual
312 = hang (hsep [ppr main_NAME, ptext SLIT("has the wrong type")])
314 hsep [ptext SLIT("Expected:"), ppr expected],
315 hsep [ptext SLIT("Inferred:"), ppr actual]