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,
56 boxedTypeKind, getTyVar, Type )
57 import TysWiredIn ( unitTy )
58 import PrelMods ( mAIN )
59 import PrelInfo ( main_NAME, thinAirIdNames, setThinAirIds )
60 import TcUnify ( unifyTauTy )
61 import Unique ( Unique )
62 import UniqSupply ( UniqSupply )
63 import Maybes ( maybeToBool )
65 import Bag ( Bag, isEmptyBag )
71 Outside-world interface:
74 -- Convenient type synonyms first:
76 = (TypecheckedMonoBinds,
78 Bag InstInfo, -- Instance declaration information
79 [TypecheckedForeignDecl], -- foreign import & exports.
81 [Id] -- The thin-air Ids
89 -> IO (Maybe TcResults)
91 typecheckModule us rn_name_supply mod
92 = initTc us initEnv (tcModule rn_name_supply mod) >>= \ (maybe_result, warns, errs) ->
97 -- write the thin-air Id map
99 Just (_, _, _, _, _, _, thin_air_ids) -> setThinAirIds thin_air_ids
103 dumpIfSet opt_D_dump_tc "Typechecked"
104 (case maybe_result of
105 Just (binds, _, _, _, _, _, _) -> ppr binds
106 Nothing -> text "Typecheck failed") >>
108 return (if isEmptyBag errs then
114 | isEmptyBag errs = return ()
115 | otherwise = printErrs (pprBagOfErrors errs)
118 The internal monster:
120 tcModule :: RnNameSupply -- for renaming derivings
121 -> RenamedHsModule -- input
122 -> TcM s TcResults -- output
124 tcModule rn_name_supply
125 (HsModule mod_name verion exports imports decls src_loc)
126 = tcAddSrcLoc src_loc $ -- record where we're starting
128 fixTc (\ ~(unf_env ,_) ->
129 -- unf_env is used for type-checking interface pragmas
130 -- which is done lazily [ie failure just drops the pragma
131 -- without having any global-failure effect].
133 -- unf_env is also used to get the pragam info
134 -- for imported dfuns and default methods
136 -- The knot for instance information. This isn't used at all
137 -- till we type-check value declarations
138 fixTc ( \ ~(rec_inst_mapper, _, _, _) ->
140 -- Type-check the type and class decls
141 tcTyAndClassDecls unf_env rec_inst_mapper decls `thenTc` \ env ->
143 -- Typecheck the instance decls, includes deriving
145 tcInstDecls1 unf_env decls mod_name rn_name_supply
146 ) `thenTc` \ (inst_info, deriv_binds) ->
148 buildInstanceEnvs inst_info `thenNF_Tc` \ inst_mapper ->
150 returnTc (inst_mapper, env, inst_info, deriv_binds)
152 -- End of inner fix loop
153 ) `thenTc` \ (_, env, inst_info, deriv_binds) ->
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
163 -- We don't create bindings for dictionary constructors;
164 -- they are always fully applied, and the bindings are just there
165 -- to support partial applications
167 tycons = getEnvTyCons env
168 classes = getEnvClasses env
169 local_tycons = filter isLocallyDefined tycons
170 local_classes = filter isLocallyDefined classes
172 mkDataBinds tycons `thenTc` \ (data_ids, data_binds) ->
174 -- Extend the global value environment with
176 -- (b) record selectors
177 -- (c) class op selectors
178 -- (d) default-method ids... where? I can't see where these are
179 -- put into the envt, and I'm worried that the zonking phase
180 -- will find they aren't there and complain.
181 tcExtendGlobalValEnv data_ids $
182 tcExtendGlobalValEnv (concat (map classSelIds classes)) $
184 -- Extend the TyCon envt with the tycons corresponding to
185 -- the classes, and the global value environment with the
186 -- corresponding data cons.
187 -- They are mentioned in types in interface files.
188 tcExtendGlobalValEnv (map (dataConId . classDataCon) classes) $
189 tcExtendTypeEnv [ (getName tycon, (kindToTcKind (tyConKind tycon), Nothing, ATyCon tycon))
191 let tycon = classTyCon clas
194 -- Interface type signatures
195 -- We tie a knot so that the Ids read out of interfaces are in scope
196 -- when we read their pragmas.
197 -- What we rely on is that pragmas are typechecked lazily; if
198 -- any type errors are found (ie there's an inconsistency)
199 -- we silently discard the pragma
200 tcInterfaceSigs unf_env decls `thenTc` \ sig_ids ->
201 tcExtendGlobalValEnv sig_ids $
203 -- foreign import declarations next.
204 tcForeignImports decls `thenTc` \ (fo_ids, foi_decls) ->
205 tcExtendGlobalValEnv fo_ids $
207 -- Value declarations next.
208 -- We also typecheck any extra binds that came out of the "deriving" process
210 (\ is_rec binds1 (binds2, thing) -> (binds1 `AndMonoBinds` binds2, thing))
211 (get_val_decls decls `ThenBinds` deriv_binds)
212 ( tcGetEnv `thenNF_Tc` \ env ->
213 tcGetUnique `thenNF_Tc` \ uniq ->
214 returnTc ((EmptyMonoBinds, env), emptyLIE)
215 ) `thenTc` \ ((val_binds, final_env), lie_valdecls) ->
218 -- foreign export declarations next.
219 tcForeignExports decls `thenTc` \ (lie_fodecls, foe_binds, foe_decls) ->
221 -- Second pass over class and instance declarations,
222 -- to compile the bindings themselves.
223 tcInstDecls2 inst_info `thenNF_Tc` \ (lie_instdecls, inst_binds) ->
224 tcClassDecls2 decls `thenNF_Tc` \ (lie_clasdecls, cls_binds) ->
227 -- Deal with constant or ambiguous InstIds. How could
228 -- there be ambiguous ones? They can only arise if a
229 -- top-level decl falls under the monomorphism
230 -- restriction, and no subsequent decl instantiates its
231 -- type. (Usually, ambiguous type variables are resolved
232 -- during the generalisation step.)
234 lie_alldecls = lie_valdecls `plusLIE`
235 lie_instdecls `plusLIE`
236 lie_clasdecls `plusLIE`
239 tcSimplifyTop lie_alldecls `thenTc` \ const_inst_binds ->
241 -- Check that Main defines main
242 (if mod_name == mAIN then
243 tcLookupValueMaybe main_NAME `thenNF_Tc` \ maybe_main ->
244 checkTc (maybeToBool maybe_main) noMainErr
249 -- Backsubstitution. This must be done last.
250 -- Even tcSimplifyTop may do some unification.
252 all_binds = data_binds `AndMonoBinds`
253 val_binds `AndMonoBinds`
254 inst_binds `AndMonoBinds`
255 cls_binds `AndMonoBinds`
256 const_inst_binds `AndMonoBinds`
259 zonkTopBinds all_binds `thenNF_Tc` \ (all_binds', really_final_env) ->
260 tcSetValueEnv really_final_env $
261 zonkForeignExports foe_decls `thenNF_Tc` \ foe_decls' ->
264 thin_air_ids = map (explicitLookupValueByKey really_final_env . nameUnique) thinAirIdNames
265 -- When looking up the thin-air names we must use
266 -- a global env that includes the zonked locally-defined Ids too
267 -- Hence using really_final_env
269 returnTc (really_final_env,
270 (all_binds', local_tycons, local_classes, inst_info,
271 (foi_decls ++ foe_decls'),
276 -- End of outer fix loop
277 ) `thenTc` \ (final_env, stuff) ->
280 get_val_decls decls = foldr ThenBinds EmptyBinds [binds | ValD binds <- decls]
286 = hsep [ptext SLIT("Module"), quotes (pprModule mAIN),
287 ptext SLIT("must include a definition for"), quotes (ppr main_NAME)]