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 )
18 import TcHsSyn ( TcMonoBinds, TypecheckedMonoBinds, zonkTopBinds )
21 import Inst ( Inst, emptyLIE, plusLIE )
22 import TcBinds ( tcTopBindsAndThen )
23 import TcClassDcl ( tcClassDecls2 )
24 import TcDefaults ( tcDefaults )
25 import TcEnv ( TcIdOcc(..), tcExtendGlobalValEnv, tcExtendTyConEnv,
26 getEnv_TyCons, getEnv_Classes, tcLookupLocalValue,
27 tcLookupTyCon, initEnv )
28 import TcExpr ( tcId )
29 import TcIfaceSig ( tcInterfaceSigs )
30 import TcInstDcls ( tcInstDecls1, tcInstDecls2 )
31 import TcInstUtil ( buildInstanceEnvs, classDataCon, InstInfo )
32 import TcSimplify ( tcSimplifyTop )
33 import TcTyClsDecls ( tcTyAndClassDecls1 )
34 import TcTyDecls ( mkDataBinds )
35 import TcType ( TcType, tcInstType )
36 import TcKind ( TcKind, kindToTcKind )
38 import RnMonad ( RnNameSupply(..) )
39 import Bag ( isEmptyBag )
40 import ErrUtils ( WarnMsg, ErrMsg,
41 pprBagOfErrors, dumpIfSet
43 import Id ( idType, GenId )
44 import Name ( Name, isLocallyDefined, pprModule, NamedThing(..) )
45 import TyCon ( TyCon, tyConKind )
46 import Class ( Class, classSelIds, classTyCon )
47 import Type ( mkTyConApp, Type )
48 import TyVar ( emptyTyVarEnv )
49 import TysWiredIn ( unitTy )
50 import PrelMods ( mAIN )
51 import PrelInfo ( main_NAME, ioTyCon_NAME )
52 import Unify ( unifyTauTy )
53 import Unique ( Unique )
54 import UniqSupply ( UniqSupply )
56 import Bag ( Bag, isEmptyBag )
57 import FiniteMap ( FiniteMap )
61 Outside-world interface:
64 -- Convenient type synonyms first:
66 = (TypecheckedMonoBinds,
68 Bag InstInfo, -- Instance declaration information
71 type TcDDumpDeriv = SDoc
78 -> IO (Maybe TcResults)
80 typecheckModule us rn_name_supply mod
82 (maybe_result, warns, errs) =
83 initTc us initEnv (tcModule rn_name_supply mod)
88 dumpIfSet opt_D_dump_tc "Typechecked"
90 Just (binds, _, _, _, _) -> ppr binds
91 Nothing -> text "Typecheck failed") >>
93 dumpIfSet opt_D_dump_deriv "Derived instances"
95 Just (_, _, _, _, dump_deriv) -> dump_deriv
98 return (if isEmptyBag errs then
104 | isEmptyBag errs = return ()
105 | otherwise = printErrs (pprBagOfErrors errs)
108 The internal monster:
110 tcModule :: RnNameSupply -- for renaming derivings
111 -> RenamedHsModule -- input
112 -> TcM s TcResults -- output
114 tcModule rn_name_supply
115 (HsModule mod_name verion exports imports fixities decls src_loc)
116 = tcAddSrcLoc src_loc $ -- record where we're starting
118 fixTc (\ ~(unf_env ,_) ->
119 -- unf_env is used for type-checking interface pragmas
120 -- which is done lazily [ie failure just drops the pragma
121 -- without having any global-failure effect].
123 -- unf_env is also used to get the pragam info
124 -- for imported dfuns and default methods
126 -- The knot for instance information. This isn't used at all
127 -- till we type-check value declarations
128 fixTc ( \ ~(rec_inst_mapper, _, _, _, _) ->
130 -- Type-check the type and class decls
131 -- trace "tcTyAndClassDecls:" $
132 tcTyAndClassDecls1 unf_env rec_inst_mapper decls `thenTc` \ env ->
135 -- Typecheck the instance decls, includes deriving
137 -- trace "tcInstDecls:" $
138 tcInstDecls1 unf_env decls mod_name rn_name_supply
139 ) `thenTc` \ (inst_info, deriv_binds, ddump_deriv) ->
142 buildInstanceEnvs inst_info `thenNF_Tc` \ inst_mapper ->
144 returnTc (inst_mapper, env, inst_info, deriv_binds, ddump_deriv)
146 -- End of inner fix loop
147 ) `thenTc` \ (_, env, inst_info, deriv_binds, ddump_deriv) ->
152 -- Default declarations
153 tcDefaults decls `thenTc` \ defaulting_tys ->
154 tcSetDefaultTys defaulting_tys $
156 -- Create any necessary record selector Ids and their bindings
157 -- "Necessary" includes data and newtype declarations
159 tycons = getEnv_TyCons env
160 classes = getEnv_Classes env
161 local_tycons = filter isLocallyDefined tycons
162 local_classes = filter isLocallyDefined classes
164 mkDataBinds tycons `thenTc` \ (data_ids, data_binds) ->
166 -- Extend the global value environment with
168 -- (b) record selectors
169 -- (c) class op selectors
170 -- (d) default-method ids
171 tcExtendGlobalValEnv data_ids $
172 tcExtendGlobalValEnv (concat (map classSelIds classes)) $
174 -- Extend the TyCon envt with the tycons corresponding to
175 -- the classes, and the global value environment with the
176 -- corresponding data cons.
177 -- They are mentioned in types in interface files.
178 tcExtendGlobalValEnv (map classDataCon classes) $
179 tcExtendTyConEnv [ (getName tycon, (kindToTcKind (tyConKind tycon), Nothing, tycon))
181 let tycon = classTyCon clas
184 -- Interface type signatures
185 -- We tie a knot so that the Ids read out of interfaces are in scope
186 -- when we read their pragmas.
187 -- What we rely on is that pragmas are typechecked lazily; if
188 -- any type errors are found (ie there's an inconsistency)
189 -- we silently discard the pragma
190 tcInterfaceSigs unf_env decls `thenTc` \ sig_ids ->
191 tcExtendGlobalValEnv sig_ids $
194 -- Value declarations next.
195 -- We also typecheck any extra binds that came out of the "deriving" process
196 -- trace "tcBinds:" $
198 (\ is_rec binds1 (binds2, thing) -> (binds1 `AndMonoBinds` binds2, thing))
199 (get_val_decls decls `ThenBinds` deriv_binds)
200 ( tcGetEnv `thenNF_Tc` \ env ->
201 returnTc ((EmptyMonoBinds, env), emptyLIE)
202 ) `thenTc` \ ((val_binds, final_env), lie_valdecls) ->
206 -- Second pass over class and instance declarations,
207 -- to compile the bindings themselves.
209 tcInstDecls2 inst_info `thenNF_Tc` \ (lie_instdecls, inst_binds) ->
210 tcClassDecls2 decls `thenNF_Tc` \ (lie_clasdecls, cls_binds) ->
214 -- Check that "main" has the right signature
215 tcCheckMainSig mod_name `thenTc_`
217 -- Deal with constant or ambiguous InstIds. How could
218 -- there be ambiguous ones? They can only arise if a
219 -- top-level decl falls under the monomorphism
220 -- restriction, and no subsequent decl instantiates its
221 -- type. (Usually, ambiguous type variables are resolved
222 -- during the generalisation step.)
225 lie_alldecls = lie_valdecls `plusLIE` lie_instdecls `plusLIE` lie_clasdecls
227 tcSimplifyTop lie_alldecls `thenTc` \ const_inst_binds ->
230 -- Backsubstitution. This must be done last.
231 -- Even tcCheckMainSig and tcSimplifyTop may do some unification.
233 all_binds = data_binds `AndMonoBinds`
234 val_binds `AndMonoBinds`
235 inst_binds `AndMonoBinds`
236 cls_binds `AndMonoBinds`
239 zonkTopBinds all_binds `thenNF_Tc` \ (all_binds', really_final_env) ->
241 returnTc (really_final_env,
242 (all_binds', local_tycons, local_classes, inst_info, ddump_deriv))
244 -- End of outer fix loop
245 ) `thenTc` \ (final_env, stuff) ->
248 get_val_decls decls = foldr ThenBinds EmptyBinds [binds | ValD binds <- decls]
253 tcCheckMainSig mod_name
255 = returnTc () -- A non-main module
258 = -- Check that main is defined
259 tcLookupTyCon ioTyCon_NAME `thenTc` \ (_,_,ioTyCon) ->
260 tcLookupLocalValue main_NAME `thenNF_Tc` \ maybe_main_id ->
261 case maybe_main_id of {
262 Nothing -> failWithTc noMainErr ;
265 -- Check that it has the right type (or a more general one)
267 expected_ty = mkTyConApp ioTyCon [unitTy]
269 tcInstType emptyTyVarEnv expected_ty `thenNF_Tc` \ expected_tau ->
270 tcId main_NAME `thenNF_Tc` \ (_, lie, main_tau) ->
271 tcSetErrCtxt mainTyCheckCtxt $
272 unifyTauTy expected_tau
274 checkTc (isEmptyBag lie) (mainTyMisMatch expected_ty (idType main_id))
279 = hsep [ptext SLIT("When checking that"), ppr main_NAME, ptext SLIT("has the required type")]
282 = hsep [ptext SLIT("Module"), quotes (pprModule mAIN),
283 ptext SLIT("must include a definition for"), quotes (ppr main_NAME)]
285 mainTyMisMatch :: Type -> TcType s -> ErrMsg
286 mainTyMisMatch expected actual
287 = hang (hsep [ppr main_NAME, ptext SLIT("has the wrong type")])
289 hsep [ptext SLIT("Expected:"), ppr expected],
290 hsep [ptext SLIT("Inferred:"), ppr actual]