4 TyThing(..), TyThingDetails(..), TcTyThing(..),
6 -- Getting stuff from the environment
8 tcEnvTyCons, tcEnvClasses, tcEnvIds, tcEnvTcIds, tcEnvTyVars,
11 -- Instance environment, and InstInfo type
12 tcGetInstEnv, tcSetInstEnv,
13 InstInfo(..), pprInstInfo,
14 simpleInstInfoTy, simpleInstInfoTyCon, isLocalInst,
17 tcExtendGlobalEnv, tcExtendGlobalValEnv,
18 tcLookupTyCon, tcLookupClass, tcLookupGlobalId, tcLookupDataCon,
19 tcLookupGlobal_maybe, tcLookupGlobal,
23 tcExtendTyVarEnv, tcExtendTyVarEnvForMeths,
24 tcExtendLocalValEnv, tcLookup,
26 -- Global type variables
27 tcGetGlobalTyVars, tcExtendGlobalTyVars,
29 -- Random useful things
30 tcAddImportedIdInfo, tcInstId,
33 newLocalId, newSpecPragmaId,
34 newDefaultMethodName, newDFunName,
37 tcSetEnv, explicitLookupId
40 #include "HsVersions.h"
42 import RnHsSyn ( RenamedMonoBinds, RenamedSig )
44 import TcType ( TcKind, TcType, TcTyVar, TcTyVarSet, TcThetaType,
45 tcInstTyVars, zonkTcTyVars,
47 import Id ( idName, mkUserLocal, isDataConWrapId_maybe )
48 import IdInfo ( vanillaIdInfo )
49 import MkId ( mkSpecPragmaId )
50 import Var ( TyVar, Id, idType, lazySetIdInfo, idInfo )
52 import Type ( Type, ThetaType,
54 splitForAllTys, splitRhoTy,
55 getDFunTyKey, splitTyConApp_maybe
57 import DataCon ( DataCon )
58 import TyCon ( TyCon )
59 import Class ( Class, ClassOpItem, ClassContext )
60 import Subst ( substTy )
61 import Name ( Name, OccName, NamedThing(..),
62 nameOccName, nameModule, getSrcLoc, mkGlobalName,
63 isLocallyDefined, nameModule,
64 NameEnv, lookupNameEnv, nameEnvElts,
65 extendNameEnvList, emptyNameEnv
67 import OccName ( mkDFunOcc, mkDefaultMethodOcc, occNameString )
68 import HscTypes ( DFunId )
69 import Module ( Module )
70 import InstEnv ( InstEnv, emptyInstEnv )
71 import HscTypes ( lookupTypeEnv, TyThing(..), GlobalSymbolTable )
72 import Util ( zipEqual )
73 import SrcLoc ( SrcLoc )
76 import IOExts ( newIORef )
79 %************************************************************************
83 %************************************************************************
86 type TcId = Id -- Type may be a TcType
91 tcGST :: GlobalSymbolTable, -- The symbol table at the moment we began this compilation
93 tcInsts :: InstEnv, -- All instances (both imported and in this module)
95 tcGEnv :: NameEnv TyThing, -- The global type environment we've accumulated while
96 {- TypeEnv -} -- compiling this module:
97 -- types and classes (both imported and local)
99 -- (Ids defined in this module are in the local envt)
101 tcLEnv :: NameEnv TcTyThing, -- The local type environment: Ids and TyVars
102 -- defined in this module
104 tcTyVars :: TcRef TcTyVarSet -- The "global tyvars"
105 -- Namely, the in-scope TyVars bound in tcLEnv, plus the tyvars
106 -- mentioned in the types of Ids bound in tcLEnv
107 -- Why mutable? see notes with tcGetGlobalTyVars
112 The Global-Env/Local-Env story
113 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
114 During type checking, we keep in the GlobalEnv
115 * All types and classes
116 * All Ids derived from types and classes (constructors, selectors)
119 At the end of type checking, we zonk the local bindings,
120 and as we do so we add to the GlobalEnv
121 * Locally defined top-level Ids
123 Why? Because they are now Ids not TcIds. This final GlobalEnv is
125 a) fed back (via the knot) to typechecking the
126 unfoldings of interface signatures
128 b) used to augment the GlobalSymbolTable
133 = AGlobal TyThing -- Used only in the return type of a lookup
134 | ATcId TcId -- Ids defined in this module
135 | ATyVar TyVar -- Type variables
136 | AThing TcKind -- Used temporarily, during kind checking
137 -- Here's an example of how the AThing guy is used
138 -- Suppose we are checking (forall a. T a Int):
139 -- 1. We first bind (a -> AThink kv), where kv is a kind variable.
140 -- 2. Then we kind-check the (T a Int) part.
141 -- 3. Then we zonk the kind variable.
142 -- 4. Now we know the kind for 'a', and we add (a -> ATyVar a::K) to the environment
144 initTcEnv :: GlobalSymbolTable -> IO TcEnv
146 = do { gtv_var <- newIORef emptyVarSet ;
147 return (TcEnv { tcGST = gst,
148 tcGEnv = emptyNameEnv,
149 tcInsts = emptyInstEnv,
150 tcLEnv = emptyNameEnv,
154 tcEnvClasses env = [cl | AClass cl <- nameEnvElts (tcGEnv env)]
155 tcEnvTyCons env = [tc | ATyCon tc <- nameEnvElts (tcGEnv env)]
156 tcEnvIds env = [id | AnId id <- nameEnvElts (tcGEnv env)]
157 tcEnvTyVars env = [tv | ATyVar tv <- nameEnvElts (tcLEnv env)]
158 tcEnvTcIds env = [id | ATcId id <- nameEnvElts (tcLEnv env)]
160 getTcGST (TcEnv { tcGST = gst }) = gst
161 getTcGEnv (TcEnv { tcGEnv = genv }) = genv
163 -- This data type is used to help tie the knot
164 -- when type checking type and class declarations
165 data TyThingDetails = SynTyDetails Type
166 | DataTyDetails ClassContext [DataCon] [Class]
167 | ClassDetails ClassContext [Id] [ClassOpItem] DataCon
171 %************************************************************************
173 \subsection{Basic lookups}
175 %************************************************************************
178 lookup_global :: TcEnv -> Name -> Maybe TyThing
179 -- Try the global envt and then the global symbol table
180 lookup_global env name
181 = case lookupNameEnv (tcGEnv env) name of
182 Just thing -> Just thing
183 Nothing -> lookupTypeEnv (tcGST env) name
185 lookup_local :: TcEnv -> Name -> Maybe TcTyThing
186 -- Try the local envt and then try the global
187 lookup_local env name
188 = case lookupNameEnv (tcLEnv env) name of
189 Just thing -> Just thing
190 Nothing -> case lookup_global env name of
191 Just thing -> Just (AGlobal thing)
194 explicitLookupId :: TcEnv -> Name -> Maybe Id
195 explicitLookupId env name = case lookup_global env name of
196 Just (AnId id) -> Just id
201 %************************************************************************
203 \subsection{Random useful functions}
205 %************************************************************************
209 -- A useful function that takes an occurrence of a global thing
210 -- and instantiates its type with fresh type variables
212 -> NF_TcM ([TcTyVar], -- It's instantiated type
217 (tyvars, rho) = splitForAllTys (idType id)
219 tcInstTyVars tyvars `thenNF_Tc` \ (tyvars', arg_tys, tenv) ->
221 rho' = substTy tenv rho
222 (theta', tau') = splitRhoTy rho'
224 returnNF_Tc (tyvars', theta', tau')
226 tcAddImportedIdInfo :: TcEnv -> Id -> Id
227 tcAddImportedIdInfo unf_env id
228 | isLocallyDefined id -- Don't look up locally defined Ids, because they
229 -- have explicit local definitions, so we get a black hole!
232 = id `lazySetIdInfo` new_info
233 -- The Id must be returned without a data dependency on maybe_id
235 new_info = case explicitLookupId unf_env (getName id) of
236 Nothing -> vanillaIdInfo
237 Just imported_id -> idInfo imported_id
238 -- ToDo: could check that types are the same
242 %************************************************************************
244 \subsection{Making new Ids}
246 %************************************************************************
251 newLocalId :: OccName -> TcType -> SrcLoc -> NF_TcM TcId
252 newLocalId name ty loc
253 = tcGetUnique `thenNF_Tc` \ uniq ->
254 returnNF_Tc (mkUserLocal name uniq ty loc)
256 newSpecPragmaId :: Name -> TcType -> NF_TcM TcId
257 newSpecPragmaId name ty
258 = tcGetUnique `thenNF_Tc` \ uniq ->
259 returnNF_Tc (mkSpecPragmaId (nameOccName name) uniq ty (getSrcLoc name))
262 Make a name for the dict fun for an instance decl
265 newDFunName :: Module -> Class -> [Type] -> SrcLoc -> NF_TcM Name
266 newDFunName mod clas (ty:_) loc
267 = tcGetDFunUniq dfun_string `thenNF_Tc` \ inst_uniq ->
268 tcGetUnique `thenNF_Tc` \ uniq ->
269 returnNF_Tc (mkGlobalName uniq mod
270 (mkDFunOcc dfun_string inst_uniq)
273 -- Any string that is somewhat unique will do
274 dfun_string = occNameString (getOccName clas) ++ occNameString (getDFunTyKey ty)
276 newDefaultMethodName :: Name -> SrcLoc -> NF_TcM Name
277 newDefaultMethodName op_name loc
278 = tcGetUnique `thenNF_Tc` \ uniq ->
279 returnNF_Tc (mkGlobalName uniq (nameModule op_name)
280 (mkDefaultMethodOcc (getOccName op_name))
285 %************************************************************************
287 \subsection{The global environment}
289 %************************************************************************
292 tcExtendGlobalEnv :: [(Name, TyThing)] -> TcM r -> TcM r
293 tcExtendGlobalEnv bindings thing_inside
294 = tcGetEnv `thenNF_Tc` \ env ->
296 ge' = extendNameEnvList (tcGEnv env) bindings
298 tcSetEnv (env {tcGEnv = ge'}) thing_inside
300 tcExtendGlobalValEnv :: [Id] -> TcM a -> TcM a
301 tcExtendGlobalValEnv ids thing_inside
302 = tcExtendGlobalEnv [(getName id, AnId id) | id <- ids] thing_inside
307 tcLookupGlobal_maybe :: Name -> NF_TcM (Maybe TyThing)
308 tcLookupGlobal_maybe name
309 = tcGetEnv `thenNF_Tc` \ env ->
310 returnNF_Tc (lookup_global env name)
313 A variety of global lookups, when we know what we are looking for.
316 tcLookupGlobal :: Name -> NF_TcM TyThing
318 = tcLookupGlobal_maybe name `thenNF_Tc` \ maybe_thing ->
320 Just thing -> returnNF_Tc thing
321 other -> notFound "tcLookupGlobal:" name
323 tcLookupGlobalId :: Name -> NF_TcM Id
324 tcLookupGlobalId name
325 = tcLookupGlobal_maybe name `thenNF_Tc` \ maybe_id ->
327 Just (AnId clas) -> returnNF_Tc clas
328 other -> notFound "tcLookupGlobalId:" name
330 tcLookupDataCon :: Name -> TcM DataCon
331 tcLookupDataCon con_name
332 = tcLookupGlobalId con_name `thenNF_Tc` \ con_id ->
333 case isDataConWrapId_maybe con_id of
334 Just data_con -> returnTc data_con
335 Nothing -> failWithTc (badCon con_id)
338 tcLookupClass :: Name -> NF_TcM Class
340 = tcLookupGlobal_maybe name `thenNF_Tc` \ maybe_clas ->
342 Just (AClass clas) -> returnNF_Tc clas
343 other -> notFound "tcLookupClass:" name
345 tcLookupTyCon :: Name -> NF_TcM TyCon
347 = tcLookupGlobal_maybe name `thenNF_Tc` \ maybe_tc ->
349 Just (ATyCon tc) -> returnNF_Tc tc
350 other -> notFound "tcLookupTyCon:" name
354 %************************************************************************
356 \subsection{The local environment}
358 %************************************************************************
361 tcLookup_maybe :: Name -> NF_TcM (Maybe TcTyThing)
363 = tcGetEnv `thenNF_Tc` \ env ->
364 returnNF_Tc (lookup_local env name)
366 tcLookup :: Name -> NF_TcM TcTyThing
368 = tcLookup_maybe name `thenNF_Tc` \ maybe_thing ->
370 Just thing -> returnNF_Tc thing
371 other -> notFound "tcLookup:" name
372 -- Extract the IdInfo from an IfaceSig imported from an interface file
377 tcExtendKindEnv :: [(Name,TcKind)] -> TcM r -> TcM r
378 tcExtendKindEnv pairs thing_inside
379 = tcGetEnv `thenNF_Tc` \ env ->
381 le' = extendNameEnvList (tcLEnv env) [(n, AThing k) | (n,k) <- pairs]
382 -- No need to extend global tyvars for kind checking
384 tcSetEnv (env {tcLEnv = le'}) thing_inside
386 tcExtendTyVarEnv :: [TyVar] -> TcM r -> TcM r
387 tcExtendTyVarEnv tyvars thing_inside
388 = tcGetEnv `thenNF_Tc` \ env@(TcEnv {tcLEnv = le, tcTyVars = gtvs}) ->
390 le' = extendNameEnvList le [ (getName tv, ATyVar tv) | tv <- tyvars]
391 new_tv_set = mkVarSet tyvars
393 -- It's important to add the in-scope tyvars to the global tyvar set
395 -- f (x::r) = let g y = y::r in ...
396 -- Here, g mustn't be generalised. This is also important during
397 -- class and instance decls, when we mustn't generalise the class tyvars
398 -- when typechecking the methods.
399 tc_extend_gtvs gtvs new_tv_set `thenNF_Tc` \ gtvs' ->
400 tcSetEnv (env {tcLEnv = le', tcTyVars = gtvs'}) thing_inside
402 -- This variant, tcExtendTyVarEnvForMeths, takes *two* bunches of tyvars:
403 -- the signature tyvars contain the original names
404 -- the instance tyvars are what those names should be mapped to
405 -- It's needed when typechecking the method bindings of class and instance decls
406 -- It does *not* extend the global tyvars; tcMethodBind does that for itself
408 tcExtendTyVarEnvForMeths :: [TyVar] -> [TcTyVar] -> TcM r -> TcM r
409 tcExtendTyVarEnvForMeths sig_tyvars inst_tyvars thing_inside
410 = tcGetEnv `thenNF_Tc` \ env ->
412 le' = extendNameEnvList (tcLEnv env) stuff
413 stuff = [ (getName sig_tv, ATyVar inst_tv)
414 | (sig_tv, inst_tv) <- zipEqual "tcMeth" sig_tyvars inst_tyvars
417 tcSetEnv (env {tcLEnv = le'}) thing_inside
422 tcExtendLocalValEnv :: [(Name,TcId)] -> TcM a -> TcM a
423 tcExtendLocalValEnv names_w_ids thing_inside
424 = tcGetEnv `thenNF_Tc` \ env ->
426 extra_global_tyvars = tyVarsOfTypes [idType id | (name,id) <- names_w_ids]
427 extra_env = [(name, ATcId id) | (name,id) <- names_w_ids]
428 le' = extendNameEnvList (tcLEnv env) extra_env
430 tc_extend_gtvs (tcTyVars env) extra_global_tyvars `thenNF_Tc` \ gtvs' ->
431 tcSetEnv (env {tcLEnv = le', tcTyVars = gtvs'}) thing_inside
435 %************************************************************************
437 \subsection{The global tyvars}
439 %************************************************************************
442 tcExtendGlobalTyVars extra_global_tvs thing_inside
443 = tcGetEnv `thenNF_Tc` \ env ->
444 tc_extend_gtvs (tcTyVars env) extra_global_tvs `thenNF_Tc` \ gtvs' ->
445 tcSetEnv (env {tcTyVars = gtvs'}) thing_inside
447 tc_extend_gtvs gtvs extra_global_tvs
448 = tcReadMutVar gtvs `thenNF_Tc` \ global_tvs ->
449 tcNewMutVar (global_tvs `unionVarSet` extra_global_tvs)
452 @tcGetGlobalTyVars@ returns a fully-zonked set of tyvars free in the environment.
453 To improve subsequent calls to the same function it writes the zonked set back into
457 tcGetGlobalTyVars :: NF_TcM TcTyVarSet
459 = tcGetEnv `thenNF_Tc` \ (TcEnv {tcTyVars = gtv_var}) ->
460 tcReadMutVar gtv_var `thenNF_Tc` \ global_tvs ->
461 zonkTcTyVars (varSetElems global_tvs) `thenNF_Tc` \ global_tys' ->
463 global_tvs' = (tyVarsOfTypes global_tys')
465 tcWriteMutVar gtv_var global_tvs' `thenNF_Tc_`
466 returnNF_Tc global_tvs'
470 %************************************************************************
472 \subsection{The instance environment}
474 %************************************************************************
477 tcGetInstEnv :: NF_TcM InstEnv
478 tcGetInstEnv = tcGetEnv `thenNF_Tc` \ env ->
479 returnNF_Tc (tcInsts env)
481 tcSetInstEnv :: InstEnv -> TcM a -> TcM a
482 tcSetInstEnv ie thing_inside
483 = tcGetEnv `thenNF_Tc` \ env ->
484 tcSetEnv (env {tcInsts = ie}) thing_inside
488 %************************************************************************
490 \subsection{The InstInfo type}
492 %************************************************************************
494 The InstInfo type summarises the information in an instance declaration
496 instance c => k (t tvs) where b
501 iClass :: Class, -- Class, k
502 iTyVars :: [TyVar], -- Type variables, tvs
503 iTys :: [Type], -- The types at which the class is being instantiated
504 iTheta :: ThetaType, -- inst_decl_theta: the original context, c, from the
505 -- instance declaration. It constrains (some of)
507 iLocal :: Bool, -- True <=> it's defined in this module
508 iDFunId :: DFunId, -- The dfun id
509 iBinds :: RenamedMonoBinds, -- Bindings, b
510 iLoc :: SrcLoc, -- Source location assoc'd with this instance's defn
511 iPrags :: [RenamedSig] -- User pragmas recorded for generating specialised instances
514 pprInstInfo info = vcat [ptext SLIT("InstInfo:") <+> ppr (idType (iDFunId info)),
515 nest 4 (ppr (iBinds info))]
517 simpleInstInfoTy :: InstInfo -> Type
518 simpleInstInfoTy (InstInfo {iTys = [ty]}) = ty
520 simpleInstInfoTyCon :: InstInfo -> TyCon
521 -- Gets the type constructor for a simple instance declaration,
522 -- i.e. one of the form instance (...) => C (T a b c) where ...
523 simpleInstInfoTyCon inst
524 = case splitTyConApp_maybe (simpleInstInfoTy inst) of
525 Just (tycon, _) -> tycon
527 isLocalInst :: Module -> InstInfo -> Bool
528 isLocalInst mod info = mod == nameModule (idName (iDFunId info))
532 %************************************************************************
536 %************************************************************************
539 badCon con_id = quotes (ppr con_id) <+> ptext SLIT("is not a data constructor")
541 notFound wheRe name = failWithTc (text wheRe <> colon <+> quotes (ppr name) <+>
542 ptext SLIT("is not in scope"))