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,
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 isLocalThing, 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 ( mkUserLocal, isDataConWrapId_maybe )
48 import IdInfo ( vanillaIdInfo )
49 import MkId ( mkSpecPragmaId )
50 import Var ( TyVar, Id, idType, lazySetIdInfo, idInfo )
53 tyVarsOfTypes, splitDFunTy,
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 isLocalName, nameModule_maybe,
64 NameEnv, lookupNameEnv, nameEnvElts,
65 extendNameEnvList, emptyNameEnv
67 import OccName ( mkDFunOcc, mkDefaultMethodOcc, occNameString )
68 import HscTypes ( DFunId, TypeEnv, HomeSymbolTable, PackageTypeEnv )
69 import Module ( Module )
70 import InstEnv ( InstEnv, emptyInstEnv )
71 import HscTypes ( lookupType, TyThing(..) )
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 :: Name -> Maybe TyThing, -- The type environment at the moment we began this compilation
93 tcInsts :: InstEnv, -- All instances (both imported and in this module)
95 tcGEnv :: TypeEnv, -- The global type environment we've accumulated while
96 {- NameEnv TyThing-} -- 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 :: HomeSymbolTable -> PackageTypeEnv -> IO TcEnv
146 = do { gtv_var <- newIORef emptyVarSet ;
147 return (TcEnv { tcGST = lookup,
148 tcGEnv = emptyNameEnv,
149 tcInsts = emptyInstEnv,
150 tcLEnv = emptyNameEnv,
154 lookup name | isLocalName name = Nothing
155 | otherwise = lookupType hst pte name
158 tcEnvClasses env = [cl | AClass cl <- nameEnvElts (tcGEnv env)]
159 tcEnvTyCons env = [tc | ATyCon tc <- nameEnvElts (tcGEnv env)]
160 tcEnvIds env = [id | AnId id <- nameEnvElts (tcGEnv env)]
161 tcEnvTyVars env = [tv | ATyVar tv <- nameEnvElts (tcLEnv env)]
162 tcEnvTcIds env = [id | ATcId id <- nameEnvElts (tcLEnv env)]
164 getTcGEnv (TcEnv { tcGEnv = genv }) = genv
166 -- This data type is used to help tie the knot
167 -- when type checking type and class declarations
168 data TyThingDetails = SynTyDetails Type
169 | DataTyDetails ClassContext [DataCon] [Class]
170 | ClassDetails ClassContext [Id] [ClassOpItem] DataCon
174 %************************************************************************
176 \subsection{Basic lookups}
178 %************************************************************************
181 lookup_global :: TcEnv -> Name -> Maybe TyThing
182 -- Try the global envt and then the global symbol table
183 lookup_global env name
184 = case lookupNameEnv (tcGEnv env) name of
185 Just thing -> Just thing
186 Nothing -> tcGST env name
188 lookup_local :: TcEnv -> Name -> Maybe TcTyThing
189 -- Try the local envt and then try the global
190 lookup_local env name
191 = case lookupNameEnv (tcLEnv env) name of
192 Just thing -> Just thing
193 Nothing -> case lookup_global env name of
194 Just thing -> Just (AGlobal thing)
197 explicitLookupId :: TcEnv -> Name -> Maybe Id
198 explicitLookupId env name = case lookup_global env name of
199 Just (AnId id) -> Just id
204 %************************************************************************
206 \subsection{Random useful functions}
208 %************************************************************************
212 -- A useful function that takes an occurrence of a global thing
213 -- and instantiates its type with fresh type variables
215 -> NF_TcM ([TcTyVar], -- It's instantiated type
220 (tyvars, rho) = splitForAllTys (idType id)
222 tcInstTyVars tyvars `thenNF_Tc` \ (tyvars', arg_tys, tenv) ->
224 rho' = substTy tenv rho
225 (theta', tau') = splitRhoTy rho'
227 returnNF_Tc (tyvars', theta', tau')
229 tcAddImportedIdInfo :: TcEnv -> Id -> Id
230 tcAddImportedIdInfo unf_env id
231 | isLocallyDefined id -- Don't look up locally defined Ids, because they
232 -- have explicit local definitions, so we get a black hole!
235 = id `lazySetIdInfo` new_info
236 -- The Id must be returned without a data dependency on maybe_id
238 new_info = case explicitLookupId unf_env (getName id) of
239 Nothing -> vanillaIdInfo
240 Just imported_id -> idInfo imported_id
241 -- ToDo: could check that types are the same
245 %************************************************************************
247 \subsection{Making new Ids}
249 %************************************************************************
254 newLocalId :: OccName -> TcType -> SrcLoc -> NF_TcM TcId
255 newLocalId name ty loc
256 = tcGetUnique `thenNF_Tc` \ uniq ->
257 returnNF_Tc (mkUserLocal name uniq ty loc)
259 newSpecPragmaId :: Name -> TcType -> NF_TcM TcId
260 newSpecPragmaId name ty
261 = tcGetUnique `thenNF_Tc` \ uniq ->
262 returnNF_Tc (mkSpecPragmaId (nameOccName name) uniq ty (getSrcLoc name))
265 Make a name for the dict fun for an instance decl
268 newDFunName :: Module -> Class -> [Type] -> SrcLoc -> NF_TcM Name
269 newDFunName mod clas (ty:_) loc
270 = tcGetDFunUniq dfun_string `thenNF_Tc` \ inst_uniq ->
271 tcGetUnique `thenNF_Tc` \ uniq ->
272 returnNF_Tc (mkGlobalName uniq mod
273 (mkDFunOcc dfun_string inst_uniq)
276 -- Any string that is somewhat unique will do
277 dfun_string = occNameString (getOccName clas) ++ occNameString (getDFunTyKey ty)
279 newDefaultMethodName :: Name -> SrcLoc -> NF_TcM Name
280 newDefaultMethodName op_name loc
281 = tcGetUnique `thenNF_Tc` \ uniq ->
282 returnNF_Tc (mkGlobalName uniq (nameModule op_name)
283 (mkDefaultMethodOcc (getOccName op_name))
288 isLocalThing :: NamedThing a => Module -> a -> Bool
289 -- True if the thing has a Local name,
290 -- or a Global name from the specified module
291 isLocalThing mod thing = case nameModule_maybe (getName thing) of
292 Nothing -> True -- A local name
293 Just m -> m == mod -- A global thing
296 %************************************************************************
298 \subsection{The global environment}
300 %************************************************************************
303 tcExtendGlobalEnv :: [(Name, TyThing)] -> TcM r -> TcM r
304 tcExtendGlobalEnv bindings thing_inside
305 = tcGetEnv `thenNF_Tc` \ env ->
307 ge' = extendNameEnvList (tcGEnv env) bindings
309 tcSetEnv (env {tcGEnv = ge'}) thing_inside
311 tcExtendGlobalValEnv :: [Id] -> TcM a -> TcM a
312 tcExtendGlobalValEnv ids thing_inside
313 = tcExtendGlobalEnv [(getName id, AnId id) | id <- ids] thing_inside
318 tcLookupGlobal_maybe :: Name -> NF_TcM (Maybe TyThing)
319 tcLookupGlobal_maybe name
320 = tcGetEnv `thenNF_Tc` \ env ->
321 returnNF_Tc (lookup_global env name)
324 A variety of global lookups, when we know what we are looking for.
327 tcLookupGlobal :: Name -> NF_TcM TyThing
329 = tcLookupGlobal_maybe name `thenNF_Tc` \ maybe_thing ->
331 Just thing -> returnNF_Tc thing
332 other -> notFound "tcLookupGlobal" name
334 tcLookupGlobalId :: Name -> NF_TcM Id
335 tcLookupGlobalId name
336 = tcLookupGlobal_maybe name `thenNF_Tc` \ maybe_id ->
338 Just (AnId clas) -> returnNF_Tc clas
339 other -> notFound "tcLookupGlobalId" name
341 tcLookupDataCon :: Name -> TcM DataCon
342 tcLookupDataCon con_name
343 = tcLookupGlobalId con_name `thenNF_Tc` \ con_id ->
344 case isDataConWrapId_maybe con_id of
345 Just data_con -> returnTc data_con
346 Nothing -> failWithTc (badCon con_id)
349 tcLookupClass :: Name -> NF_TcM Class
351 = tcLookupGlobal_maybe name `thenNF_Tc` \ maybe_clas ->
353 Just (AClass clas) -> returnNF_Tc clas
354 other -> notFound "tcLookupClass" name
356 tcLookupTyCon :: Name -> NF_TcM TyCon
358 = tcLookupGlobal_maybe name `thenNF_Tc` \ maybe_tc ->
360 Just (ATyCon tc) -> returnNF_Tc tc
361 other -> notFound "tcLookupTyCon" name
365 %************************************************************************
367 \subsection{The local environment}
369 %************************************************************************
372 tcLookup_maybe :: Name -> NF_TcM (Maybe TcTyThing)
374 = tcGetEnv `thenNF_Tc` \ env ->
375 returnNF_Tc (lookup_local env name)
377 tcLookup :: Name -> NF_TcM TcTyThing
379 = tcLookup_maybe name `thenNF_Tc` \ maybe_thing ->
381 Just thing -> returnNF_Tc thing
382 other -> notFound "tcLookup" name
383 -- Extract the IdInfo from an IfaceSig imported from an interface file
388 tcExtendKindEnv :: [(Name,TcKind)] -> TcM r -> TcM r
389 tcExtendKindEnv pairs thing_inside
390 = tcGetEnv `thenNF_Tc` \ env ->
392 le' = extendNameEnvList (tcLEnv env) [(n, AThing k) | (n,k) <- pairs]
393 -- No need to extend global tyvars for kind checking
395 tcSetEnv (env {tcLEnv = le'}) thing_inside
397 tcExtendTyVarEnv :: [TyVar] -> TcM r -> TcM r
398 tcExtendTyVarEnv tyvars thing_inside
399 = tcGetEnv `thenNF_Tc` \ env@(TcEnv {tcLEnv = le, tcTyVars = gtvs}) ->
401 le' = extendNameEnvList le [ (getName tv, ATyVar tv) | tv <- tyvars]
402 new_tv_set = mkVarSet tyvars
404 -- It's important to add the in-scope tyvars to the global tyvar set
406 -- f (x::r) = let g y = y::r in ...
407 -- Here, g mustn't be generalised. This is also important during
408 -- class and instance decls, when we mustn't generalise the class tyvars
409 -- when typechecking the methods.
410 tc_extend_gtvs gtvs new_tv_set `thenNF_Tc` \ gtvs' ->
411 tcSetEnv (env {tcLEnv = le', tcTyVars = gtvs'}) thing_inside
413 -- This variant, tcExtendTyVarEnvForMeths, takes *two* bunches of tyvars:
414 -- the signature tyvars contain the original names
415 -- the instance tyvars are what those names should be mapped to
416 -- It's needed when typechecking the method bindings of class and instance decls
417 -- It does *not* extend the global tyvars; tcMethodBind does that for itself
419 tcExtendTyVarEnvForMeths :: [TyVar] -> [TcTyVar] -> TcM r -> TcM r
420 tcExtendTyVarEnvForMeths sig_tyvars inst_tyvars thing_inside
421 = tcGetEnv `thenNF_Tc` \ env ->
423 le' = extendNameEnvList (tcLEnv env) stuff
424 stuff = [ (getName sig_tv, ATyVar inst_tv)
425 | (sig_tv, inst_tv) <- zipEqual "tcMeth" sig_tyvars inst_tyvars
428 tcSetEnv (env {tcLEnv = le'}) thing_inside
433 tcExtendLocalValEnv :: [(Name,TcId)] -> TcM a -> TcM a
434 tcExtendLocalValEnv names_w_ids thing_inside
435 = tcGetEnv `thenNF_Tc` \ env ->
437 extra_global_tyvars = tyVarsOfTypes [idType id | (name,id) <- names_w_ids]
438 extra_env = [(name, ATcId id) | (name,id) <- names_w_ids]
439 le' = extendNameEnvList (tcLEnv env) extra_env
441 tc_extend_gtvs (tcTyVars env) extra_global_tyvars `thenNF_Tc` \ gtvs' ->
442 tcSetEnv (env {tcLEnv = le', tcTyVars = gtvs'}) thing_inside
446 %************************************************************************
448 \subsection{The global tyvars}
450 %************************************************************************
453 tcExtendGlobalTyVars extra_global_tvs thing_inside
454 = tcGetEnv `thenNF_Tc` \ env ->
455 tc_extend_gtvs (tcTyVars env) extra_global_tvs `thenNF_Tc` \ gtvs' ->
456 tcSetEnv (env {tcTyVars = gtvs'}) thing_inside
458 tc_extend_gtvs gtvs extra_global_tvs
459 = tcReadMutVar gtvs `thenNF_Tc` \ global_tvs ->
460 tcNewMutVar (global_tvs `unionVarSet` extra_global_tvs)
463 @tcGetGlobalTyVars@ returns a fully-zonked set of tyvars free in the environment.
464 To improve subsequent calls to the same function it writes the zonked set back into
468 tcGetGlobalTyVars :: NF_TcM TcTyVarSet
470 = tcGetEnv `thenNF_Tc` \ (TcEnv {tcTyVars = gtv_var}) ->
471 tcReadMutVar gtv_var `thenNF_Tc` \ global_tvs ->
472 zonkTcTyVars (varSetElems global_tvs) `thenNF_Tc` \ global_tys' ->
474 global_tvs' = (tyVarsOfTypes global_tys')
476 tcWriteMutVar gtv_var global_tvs' `thenNF_Tc_`
477 returnNF_Tc global_tvs'
481 %************************************************************************
483 \subsection{The instance environment}
485 %************************************************************************
488 tcGetInstEnv :: NF_TcM InstEnv
489 tcGetInstEnv = tcGetEnv `thenNF_Tc` \ env ->
490 returnNF_Tc (tcInsts env)
492 tcSetInstEnv :: InstEnv -> TcM a -> TcM a
493 tcSetInstEnv ie thing_inside
494 = tcGetEnv `thenNF_Tc` \ env ->
495 tcSetEnv (env {tcInsts = ie}) thing_inside
499 %************************************************************************
501 \subsection{The InstInfo type}
503 %************************************************************************
505 The InstInfo type summarises the information in an instance declaration
507 instance c => k (t tvs) where b
512 iLocal :: Bool, -- True <=> it's defined in this module
513 iDFunId :: DFunId, -- The dfun id
514 iBinds :: RenamedMonoBinds, -- Bindings, b
515 iPrags :: [RenamedSig] -- User pragmas recorded for generating specialised instances
518 pprInstInfo info = vcat [ptext SLIT("InstInfo:") <+> ppr (idType (iDFunId info)),
519 nest 4 (ppr (iBinds info))]
521 simpleInstInfoTy :: InstInfo -> Type
522 simpleInstInfoTy info = case splitDFunTy (idType (iDFunId info)) of
523 (_, _, _, [ty]) -> ty
525 simpleInstInfoTyCon :: InstInfo -> TyCon
526 -- Gets the type constructor for a simple instance declaration,
527 -- i.e. one of the form instance (...) => C (T a b c) where ...
528 simpleInstInfoTyCon inst
529 = case splitTyConApp_maybe (simpleInstInfoTy inst) of
530 Just (tycon, _) -> tycon
534 %************************************************************************
538 %************************************************************************
541 badCon con_id = quotes (ppr con_id) <+> ptext SLIT("is not a data constructor")
543 notFound wheRe name = failWithTc (text wheRe <> colon <+> quotes (ppr name) <+>
544 ptext SLIT("is not in scope"))