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,
45 import RnMonad ( RnNameSupply )
46 import Bag ( isEmptyBag )
47 import ErrUtils ( Message,
48 pprBagOfErrors, dumpIfSet
50 import Id ( Id, idType )
51 import Name ( Name, nameUnique, isLocallyDefined, pprModule, NamedThing(..) )
52 import TyCon ( TyCon, tyConKind )
53 import DataCon ( dataConId )
54 import Class ( Class, classSelIds, classTyCon )
55 import Type ( mkTyConApp, mkForAllTy, mkTyVarTy,
56 boxedTypeKind, getTyVar, Type )
57 import TysWiredIn ( unitTy )
58 import PrelMods ( mAIN )
59 import PrelInfo ( main_NAME, ioTyCon_NAME,
60 thinAirIdNames, setThinAirIds
62 import TcUnify ( unifyTauTy )
63 import Unique ( Unique )
64 import UniqSupply ( UniqSupply )
66 import Bag ( Bag, isEmptyBag )
72 Outside-world interface:
75 -- Convenient type synonyms first:
77 = (TypecheckedMonoBinds,
79 Bag InstInfo, -- Instance declaration information
80 [TypecheckedForeignDecl], -- foreign import & exports.
82 [Id] -- The thin-air Ids
90 -> IO (Maybe TcResults)
92 typecheckModule us rn_name_supply mod
93 = initTc us initEnv (tcModule rn_name_supply mod) >>= \ (maybe_result, warns, errs) ->
98 -- write the thin-air Id map
100 Just (_, _, _, _, _, _, thin_air_ids) -> setThinAirIds thin_air_ids
104 dumpIfSet opt_D_dump_tc "Typechecked"
105 (case maybe_result of
106 Just (binds, _, _, _, _, _, _) -> ppr binds
107 Nothing -> text "Typecheck failed") >>
109 return (if isEmptyBag errs then
115 | isEmptyBag errs = return ()
116 | otherwise = printErrs (pprBagOfErrors errs)
119 The internal monster:
121 tcModule :: RnNameSupply -- for renaming derivings
122 -> RenamedHsModule -- input
123 -> TcM s TcResults -- output
125 tcModule rn_name_supply
126 (HsModule mod_name verion exports imports decls src_loc)
127 = tcAddSrcLoc src_loc $ -- record where we're starting
129 fixTc (\ ~(unf_env ,_) ->
130 -- unf_env is used for type-checking interface pragmas
131 -- which is done lazily [ie failure just drops the pragma
132 -- without having any global-failure effect].
134 -- unf_env is also used to get the pragam info
135 -- for imported dfuns and default methods
137 -- The knot for instance information. This isn't used at all
138 -- till we type-check value declarations
139 fixTc ( \ ~(rec_inst_mapper, _, _, _) ->
141 -- Type-check the type and class decls
142 tcTyAndClassDecls unf_env rec_inst_mapper decls `thenTc` \ env ->
144 -- Typecheck the instance decls, includes deriving
146 tcInstDecls1 unf_env decls mod_name rn_name_supply
147 ) `thenTc` \ (inst_info, deriv_binds) ->
149 buildInstanceEnvs inst_info `thenNF_Tc` \ inst_mapper ->
151 returnTc (inst_mapper, env, inst_info, deriv_binds)
153 -- End of inner fix loop
154 ) `thenTc` \ (_, env, inst_info, deriv_binds) ->
158 -- Default declarations
159 tcDefaults decls `thenTc` \ defaulting_tys ->
160 tcSetDefaultTys defaulting_tys $
162 -- Create any necessary record selector Ids and their bindings
163 -- "Necessary" includes data and newtype declarations
164 -- We don't create bindings for dictionary constructors;
165 -- they are always fully applied, and the bindings are just there
166 -- to support partial applications
168 tycons = getEnvTyCons env
169 classes = getEnvClasses env
170 local_tycons = filter isLocallyDefined tycons
171 local_classes = filter isLocallyDefined classes
173 mkDataBinds tycons `thenTc` \ (data_ids, data_binds) ->
175 -- Extend the global value environment with
177 -- (b) record selectors
178 -- (c) class op selectors
179 -- (d) default-method ids... where? I can't see where these are
180 -- put into the envt, and I'm worried that the zonking phase
181 -- will find they aren't there and complain.
182 tcExtendGlobalValEnv data_ids $
183 tcExtendGlobalValEnv (concat (map classSelIds classes)) $
185 -- Extend the TyCon envt with the tycons corresponding to
186 -- the classes, and the global value environment with the
187 -- corresponding data cons.
188 -- They are mentioned in types in interface files.
189 tcExtendGlobalValEnv (map (dataConId . classDataCon) classes) $
190 tcExtendTypeEnv [ (getName tycon, (kindToTcKind (tyConKind tycon), Nothing, ATyCon tycon))
192 let tycon = classTyCon clas
195 -- Interface type signatures
196 -- We tie a knot so that the Ids read out of interfaces are in scope
197 -- when we read their pragmas.
198 -- What we rely on is that pragmas are typechecked lazily; if
199 -- any type errors are found (ie there's an inconsistency)
200 -- we silently discard the pragma
201 tcInterfaceSigs unf_env decls `thenTc` \ sig_ids ->
202 tcExtendGlobalValEnv sig_ids $
204 -- foreign import declarations next.
205 tcForeignImports decls `thenTc` \ (fo_ids, foi_decls) ->
206 tcExtendGlobalValEnv fo_ids $
208 -- Value declarations next.
209 -- We also typecheck any extra binds that came out of the "deriving" process
211 (\ is_rec binds1 (binds2, thing) -> (binds1 `AndMonoBinds` binds2, thing))
212 (get_val_decls decls `ThenBinds` deriv_binds)
213 ( tcGetEnv `thenNF_Tc` \ env ->
214 tcGetUnique `thenNF_Tc` \ uniq ->
215 returnTc ((EmptyMonoBinds, env), emptyLIE)
216 ) `thenTc` \ ((val_binds, final_env), lie_valdecls) ->
219 -- foreign export declarations next.
220 tcForeignExports decls `thenTc` \ (lie_fodecls, foe_binds, foe_decls) ->
222 -- Second pass over class and instance declarations,
223 -- to compile the bindings themselves.
224 tcInstDecls2 inst_info `thenNF_Tc` \ (lie_instdecls, inst_binds) ->
225 tcClassDecls2 decls `thenNF_Tc` \ (lie_clasdecls, cls_binds) ->
227 -- Check that "main" has the right signature
228 tcCheckMainSig mod_name `thenTc_`
230 -- Deal with constant or ambiguous InstIds. How could
231 -- there be ambiguous ones? They can only arise if a
232 -- top-level decl falls under the monomorphism
233 -- restriction, and no subsequent decl instantiates its
234 -- type. (Usually, ambiguous type variables are resolved
235 -- during the generalisation step.)
237 lie_alldecls = lie_valdecls `plusLIE`
238 lie_instdecls `plusLIE`
239 lie_clasdecls `plusLIE`
242 tcSimplifyTop lie_alldecls `thenTc` \ const_inst_binds ->
245 -- Backsubstitution. This must be done last.
246 -- Even tcCheckMainSig and tcSimplifyTop may do some unification.
248 all_binds = data_binds `AndMonoBinds`
249 val_binds `AndMonoBinds`
250 inst_binds `AndMonoBinds`
251 cls_binds `AndMonoBinds`
252 const_inst_binds `AndMonoBinds`
255 zonkTopBinds all_binds `thenNF_Tc` \ (all_binds', really_final_env) ->
256 tcSetValueEnv really_final_env $
257 zonkForeignExports foe_decls `thenNF_Tc` \ foe_decls' ->
260 thin_air_ids = map (explicitLookupValueByKey really_final_env . nameUnique) thinAirIdNames
261 -- When looking up the thin-air names we must use
262 -- a global env that includes the zonked locally-defined Ids too
263 -- Hence using really_final_env
265 returnTc (really_final_env,
266 (all_binds', local_tycons, local_classes, inst_info,
267 foi_decls ++ foe_decls',
272 -- End of outer fix loop
273 ) `thenTc` \ (final_env, stuff) ->
276 get_val_decls decls = foldr ThenBinds EmptyBinds [binds | ValD binds <- decls]
281 tcCheckMainSig mod_name
283 = returnTc () -- A non-main module
286 = -- Check that main is defined
287 tcLookupTyCon ioTyCon_NAME `thenTc` \ ioTyCon ->
288 tcLookupValueMaybe main_NAME `thenNF_Tc` \ maybe_main_id ->
289 case maybe_main_id of {
290 Nothing -> failWithTc noMainErr ;
293 -- Check that it has the right type (or a more general one)
294 -- As of Haskell 98, anything that unifies with (IO a) is OK.
295 newTyVarTy boxedTypeKind `thenNF_Tc` \ t_tv ->
297 tv = getTyVar "tcCheckMainSig" t_tv
298 expected_tau = typeToTcType ((mkTyConApp ioTyCon [t_tv]))
300 tcId main_NAME `thenNF_Tc` \ (_, lie, main_tau) ->
301 tcSetErrCtxt mainTyCheckCtxt $
302 unifyTauTy expected_tau
304 checkTc (isEmptyBag lie) (mainTyMisMatch expected_tau (idType main_id))
309 = hsep [ptext SLIT("When checking that"), ppr main_NAME, ptext SLIT("has the required type")]
312 = hsep [ptext SLIT("Module"), quotes (pprModule mAIN),
313 ptext SLIT("must include a definition for"), quotes (ppr main_NAME)]
315 mainTyMisMatch :: TcType -> TcType -> Message
316 mainTyMisMatch expected actual
317 = hang (hsep [ppr main_NAME, ptext SLIT("has the wrong type")])
319 hsep [ptext SLIT("Expected:"), ppr expected],
320 hsep [ptext SLIT("Inferred:"), ppr actual]