3 TyThing(..), TcTyThing(..), TcId,
5 -- Instance environment, and InstInfo type
6 InstInfo(..), pprInstInfo, pprInstInfoDetails,
7 simpleInstInfoTy, simpleInstInfoTyCon,
13 tcLookupLocatedGlobal, tcLookupGlobal,
14 tcLookupGlobalId, tcLookupTyCon, tcLookupClass, tcLookupDataCon,
15 tcLookupLocatedGlobalId, tcLookupLocatedTyCon,
16 tcLookupLocatedClass, tcLookupLocatedDataCon,
20 tcExtendTyVarEnv, tcExtendTyVarEnv2,
21 tcExtendLocalValEnv, tcExtendLocalValEnv2,
22 tcLookup, tcLookupLocated, tcLookupLocalIds,
23 tcLookupId, tcLookupTyVar,
24 lclEnvElts, getInLocalScope, findGlobals,
27 tcExtendRecEnv, -- For knot-tying
32 -- Global type variables
35 -- Template Haskell stuff
36 checkWellStaged, spliceOK, bracketOK, tcMetaTy, thLevel,
43 newLocalName, newDFunName
46 #include "HsVersions.h"
48 import HsSyn ( LRuleDecl, LHsBinds, LSig, pprLHsBinds )
49 import TcIface ( tcImportDecl )
51 import TcMType ( zonkTcType, zonkTcTyVar, zonkTcTyVarsAndFV )
52 import TcType ( Type, TcKind, TcTyVar, TcTyVarSet,
53 tyVarsOfType, tyVarsOfTypes, tcSplitDFunTy, mkGenTyConApp,
54 getDFunTyKey, tcTyConAppTyCon, tyVarBindingInfo,
55 tidyOpenType, tidyOpenTyVar
57 import qualified Type ( getTyVar_maybe )
58 import Id ( idName, isLocalId )
59 import Var ( TyVar, Id, idType )
62 import RdrName ( extendLocalRdrEnv )
63 import DataCon ( DataCon )
64 import TyCon ( TyCon )
65 import Class ( Class )
66 import Name ( Name, NamedThing(..), getSrcLoc, mkInternalName, nameIsLocalOrFrom )
68 import OccName ( mkDFunOcc, occNameString )
69 import HscTypes ( DFunId, extendTypeEnvList, lookupType,
70 TyThing(..), tyThingId, tyThingDataCon,
71 ExternalPackageState(..) )
73 import SrcLoc ( SrcLoc, Located(..) )
75 import Maybe ( isJust )
79 %************************************************************************
83 %************************************************************************
85 Using the Located versions (eg. tcLookupLocatedGlobal) is preferred,
86 unless you know that the SrcSpan in the monad is already set to the
90 tcLookupLocatedGlobal :: Located Name -> TcM TyThing
91 -- c.f. IfaceEnvEnv.tcIfaceGlobal
92 tcLookupLocatedGlobal name
93 = addLocM tcLookupGlobal name
95 tcLookupGlobal :: Name -> TcM TyThing
97 = do { env <- getGblEnv
98 ; if nameIsLocalOrFrom (tcg_mod env) name
100 then -- It's defined in this module
101 case lookupNameEnv (tcg_type_env env) name of
102 Just thing -> return thing
103 Nothing -> notFound "tcLookupGlobal" name
105 else do -- It's imported
106 { (eps,hpt) <- getEpsAndHpt
107 ; case lookupType hpt (eps_PTE eps) name of
108 Just thing -> return thing
109 Nothing -> do { traceIf (text "tcLookupGlobal" <+> ppr name)
110 ; initIfaceTcRn (tcImportDecl name) }
115 tcLookupGlobalId :: Name -> TcM Id
116 -- Never used for Haskell-source DataCons, hence no ADataCon case
117 tcLookupGlobalId name
118 = tcLookupGlobal name `thenM` \ thing ->
119 return (tyThingId thing)
121 tcLookupDataCon :: Name -> TcM DataCon
122 tcLookupDataCon con_name
123 = tcLookupGlobal con_name `thenM` \ thing ->
124 return (tyThingDataCon thing)
126 tcLookupClass :: Name -> TcM Class
128 = tcLookupGlobal name `thenM` \ thing ->
130 AClass cls -> return cls
131 other -> wrongThingErr "class" (AGlobal thing) name
133 tcLookupTyCon :: Name -> TcM TyCon
135 = tcLookupGlobal name `thenM` \ thing ->
137 ATyCon tc -> return tc
138 other -> wrongThingErr "type constructor" (AGlobal thing) name
140 tcLookupLocatedGlobalId :: Located Name -> TcM Id
141 tcLookupLocatedGlobalId = addLocM tcLookupId
143 tcLookupLocatedDataCon :: Located Name -> TcM DataCon
144 tcLookupLocatedDataCon = addLocM tcLookupDataCon
146 tcLookupLocatedClass :: Located Name -> TcM Class
147 tcLookupLocatedClass = addLocM tcLookupClass
149 tcLookupLocatedTyCon :: Located Name -> TcM TyCon
150 tcLookupLocatedTyCon = addLocM tcLookupTyCon
153 %************************************************************************
155 Extending the global environment
157 %************************************************************************
161 tcExtendGlobalEnv :: [TyThing] -> TcM r -> TcM r
162 -- Given a mixture of Ids, TyCons, Classes, all from the
163 -- module being compiled, extend the global environment
164 tcExtendGlobalEnv things thing_inside
165 = do { env <- getGblEnv
166 ; let ge' = extendTypeEnvList (tcg_type_env env) things
167 ; setGblEnv (env {tcg_type_env = ge'}) thing_inside }
169 tcExtendGlobalValEnv :: [Id] -> TcM a -> TcM a
170 -- Same deal as tcExtendGlobalEnv, but for Ids
171 tcExtendGlobalValEnv ids thing_inside
172 = tcExtendGlobalEnv [AnId id | id <- ids] thing_inside
176 tcExtendRecEnv :: [(Name,TyThing)] -> TcM r -> TcM r
177 -- Extend the global environments for the type/class knot tying game
178 tcExtendRecEnv gbl_stuff thing_inside
179 = updGblEnv upd thing_inside
181 upd env = env { tcg_type_env = extend (tcg_type_env env) }
182 extend env = extendNameEnvList env gbl_stuff
186 %************************************************************************
188 \subsection{The local environment}
190 %************************************************************************
193 tcLookupLocated :: Located Name -> TcM TcTyThing
194 tcLookupLocated = addLocM tcLookup
196 tcLookup :: Name -> TcM TcTyThing
198 = getLclEnv `thenM` \ local_env ->
199 case lookupNameEnv (tcl_env local_env) name of
200 Just thing -> returnM thing
201 Nothing -> tcLookupGlobal name `thenM` \ thing ->
202 returnM (AGlobal thing)
204 tcLookupTyVar :: Name -> TcM Id
206 = tcLookup name `thenM` \ thing ->
208 ATyVar tv -> returnM tv
209 other -> pprPanic "tcLookupTyVar" (ppr name)
211 tcLookupId :: Name -> TcM Id
212 -- Used when we aren't interested in the binding level
213 -- Never a DataCon. (Why does that matter? see TcExpr.tcId)
215 = tcLookup name `thenM` \ thing ->
217 ATcId tc_id _ _ -> returnM tc_id
218 AGlobal (AnId id) -> returnM id
219 other -> pprPanic "tcLookupId" (ppr name)
221 tcLookupLocalIds :: [Name] -> TcM [TcId]
222 -- We expect the variables to all be bound, and all at
223 -- the same level as the lookup. Only used in one place...
225 = getLclEnv `thenM` \ env ->
226 returnM (map (lookup (tcl_env env) (thLevel (tcl_th_ctxt env))) ns)
229 = case lookupNameEnv lenv name of
230 Just (ATcId id lvl1 _) -> ASSERT( lvl == lvl1 ) id
231 other -> pprPanic "tcLookupLocalIds" (ppr name)
233 lclEnvElts :: TcLclEnv -> [TcTyThing]
234 lclEnvElts env = nameEnvElts (tcl_env env)
236 getInLocalScope :: TcM (Name -> Bool)
238 getInLocalScope = getLclEnv `thenM` \ env ->
240 lcl_env = tcl_env env
242 return (`elemNameEnv` lcl_env)
246 tcExtendKindEnv :: [(Name, TcKind)] -> TcM r -> TcM r
247 tcExtendKindEnv things thing_inside
248 = updLclEnv upd thing_inside
250 upd lcl_env = lcl_env { tcl_env = extend (tcl_env lcl_env) }
251 extend env = extendNameEnvList env [(n, AThing k) | (n,k) <- things]
253 tcExtendTyVarEnv :: [TyVar] -> TcM r -> TcM r
254 tcExtendTyVarEnv tvs thing_inside
255 = tc_extend_tv_env [(getName tv, ATyVar tv) | tv <- tvs] tvs thing_inside
257 tcExtendTyVarEnv2 :: [(TyVar,TcTyVar)] -> TcM r -> TcM r
258 tcExtendTyVarEnv2 tv_pairs thing_inside
259 = tc_extend_tv_env [(getName tv1, ATyVar tv2) | (tv1,tv2) <- tv_pairs]
260 [tv | (_,tv) <- tv_pairs]
263 tc_extend_tv_env binds tyvars thing_inside
264 = getLclEnv `thenM` \ env@(TcLclEnv {tcl_env = le,
266 tcl_rdr = rdr_env}) ->
268 le' = extendNameEnvList le binds
269 rdr_env' = extendLocalRdrEnv rdr_env (map fst binds)
270 new_tv_set = mkVarSet tyvars
272 -- It's important to add the in-scope tyvars to the global tyvar set
274 -- f (_::r) = let g y = y::r in ...
275 -- Here, g mustn't be generalised. This is also important during
276 -- class and instance decls, when we mustn't generalise the class tyvars
277 -- when typechecking the methods.
278 tc_extend_gtvs gtvs new_tv_set `thenM` \ gtvs' ->
279 setLclEnv (env {tcl_env = le', tcl_tyvars = gtvs', tcl_rdr = rdr_env'}) thing_inside
284 tcExtendLocalValEnv :: [TcId] -> TcM a -> TcM a
285 tcExtendLocalValEnv ids thing_inside
286 = getLclEnv `thenM` \ env ->
288 extra_global_tyvars = tyVarsOfTypes [idType id | id <- ids]
289 th_lvl = thLevel (tcl_th_ctxt env)
290 proc_lvl = proc_level (tcl_arrow_ctxt env)
291 extra_env = [(idName id, ATcId id th_lvl proc_lvl) | id <- ids]
292 le' = extendNameEnvList (tcl_env env) extra_env
293 rdr_env' = extendLocalRdrEnv (tcl_rdr env) (map idName ids)
295 tc_extend_gtvs (tcl_tyvars env) extra_global_tyvars `thenM` \ gtvs' ->
296 setLclEnv (env {tcl_env = le', tcl_tyvars = gtvs', tcl_rdr = rdr_env'}) thing_inside
298 tcExtendLocalValEnv2 :: [(Name,TcId)] -> TcM a -> TcM a
299 tcExtendLocalValEnv2 names_w_ids thing_inside
300 = getLclEnv `thenM` \ env ->
302 extra_global_tyvars = tyVarsOfTypes [idType id | (name,id) <- names_w_ids]
303 th_lvl = thLevel (tcl_th_ctxt env)
304 proc_lvl = proc_level (tcl_arrow_ctxt env)
305 extra_env = [(name, ATcId id th_lvl proc_lvl) | (name,id) <- names_w_ids]
306 le' = extendNameEnvList (tcl_env env) extra_env
307 rdr_env' = extendLocalRdrEnv (tcl_rdr env) (map fst names_w_ids)
309 tc_extend_gtvs (tcl_tyvars env) extra_global_tyvars `thenM` \ gtvs' ->
310 setLclEnv (env {tcl_env = le', tcl_tyvars = gtvs', tcl_rdr = rdr_env'}) thing_inside
315 -----------------------
316 -- findGlobals looks at the value environment and finds values
317 -- whose types mention the offending type variable. It has to be
318 -- careful to zonk the Id's type first, so it has to be in the monad.
319 -- We must be careful to pass it a zonked type variable, too.
321 findGlobals :: TcTyVarSet
323 -> TcM (TidyEnv, [SDoc])
325 findGlobals tvs tidy_env
326 = getLclEnv `thenM` \ lcl_env ->
327 go tidy_env [] (lclEnvElts lcl_env)
329 go tidy_env acc [] = returnM (tidy_env, acc)
330 go tidy_env acc (thing : things)
331 = find_thing ignore_it tidy_env thing `thenM` \ (tidy_env1, maybe_doc) ->
333 Just d -> go tidy_env1 (d:acc) things
334 Nothing -> go tidy_env1 acc things
336 ignore_it ty = not (tvs `intersectsVarSet` tyVarsOfType ty)
338 -----------------------
339 find_thing ignore_it tidy_env (ATcId id _ _)
340 = zonkTcType (idType id) `thenM` \ id_ty ->
341 if ignore_it id_ty then
342 returnM (tidy_env, Nothing)
344 (tidy_env', tidy_ty) = tidyOpenType tidy_env id_ty
345 msg = sep [ppr id <+> dcolon <+> ppr tidy_ty,
346 nest 2 (parens (ptext SLIT("bound at") <+>
347 ppr (getSrcLoc id)))]
349 returnM (tidy_env', Just msg)
351 find_thing ignore_it tidy_env (ATyVar tv)
352 = zonkTcTyVar tv `thenM` \ tv_ty ->
353 if ignore_it tv_ty then
354 returnM (tidy_env, Nothing)
356 (tidy_env1, tv1) = tidyOpenTyVar tidy_env tv
357 (tidy_env2, tidy_ty) = tidyOpenType tidy_env1 tv_ty
358 msg = sep [ppr tv1 <+> eq_stuff, nest 2 bound_at]
360 eq_stuff | Just tv' <- Type.getTyVar_maybe tv_ty,
362 | otherwise = equals <+> ppr tidy_ty
363 -- It's ok to use Type.getTyVar_maybe because ty is zonked by now
365 bound_at = tyVarBindingInfo tv
367 returnM (tidy_env2, Just msg)
371 %************************************************************************
373 \subsection{The global tyvars}
375 %************************************************************************
378 tc_extend_gtvs gtvs extra_global_tvs
379 = readMutVar gtvs `thenM` \ global_tvs ->
380 newMutVar (global_tvs `unionVarSet` extra_global_tvs)
383 @tcGetGlobalTyVars@ returns a fully-zonked set of tyvars free in the environment.
384 To improve subsequent calls to the same function it writes the zonked set back into
388 tcGetGlobalTyVars :: TcM TcTyVarSet
390 = getLclEnv `thenM` \ (TcLclEnv {tcl_tyvars = gtv_var}) ->
391 readMutVar gtv_var `thenM` \ gbl_tvs ->
392 zonkTcTyVarsAndFV (varSetElems gbl_tvs) `thenM` \ gbl_tvs' ->
393 writeMutVar gtv_var gbl_tvs' `thenM_`
398 %************************************************************************
402 %************************************************************************
405 tcExtendRules :: [LRuleDecl Id] -> TcM a -> TcM a
406 -- Just pop the new rules into the EPS and envt resp
407 -- All the rules come from an interface file, not soruce
408 -- Nevertheless, some may be for this module, if we read
409 -- its interface instead of its source code
410 tcExtendRules lcl_rules thing_inside
411 = do { env <- getGblEnv
413 env' = env { tcg_rules = lcl_rules ++ tcg_rules env }
414 ; setGblEnv env' thing_inside }
418 %************************************************************************
420 Arrow notation proc levels
422 %************************************************************************
425 checkProcLevel :: TcId -> ProcLevel -> TcM ()
426 checkProcLevel id id_lvl
427 = do { banned <- getBannedProcLevels
428 ; checkTc (not (id_lvl `elem` banned))
429 (procLevelErr id id_lvl) }
431 procLevelErr id id_lvl
432 = hang (ptext SLIT("Command-bound variable") <+> quotes (ppr id) <+> ptext SLIT("is not in scope here"))
433 4 (ptext SLIT("Reason: it is used in the left argument of (-<)"))
437 %************************************************************************
441 %************************************************************************
444 instance Outputable ThStage where
445 ppr Comp = text "Comp"
446 ppr (Brack l _ _) = text "Brack" <+> int l
447 ppr (Splice l) = text "Splice" <+> int l
450 thLevel :: ThStage -> ThLevel
451 thLevel Comp = topLevel
452 thLevel (Splice l) = l
453 thLevel (Brack l _ _) = l
456 checkWellStaged :: SDoc -- What the stage check is for
457 -> ThLevel -- Binding level
458 -> ThStage -- Use stage
459 -> TcM () -- Fail if badly staged, adding an error
460 checkWellStaged pp_thing bind_lvl use_stage
461 | bind_lvl <= use_lvl -- OK!
464 | bind_lvl == topLevel -- GHC restriction on top level splices
466 sep [ptext SLIT("GHC stage restriction:") <+> pp_thing,
467 nest 2 (ptext SLIT("is used in a top-level splice, and must be imported, not defined locally"))]
469 | otherwise -- Badly staged
471 ptext SLIT("Stage error:") <+> pp_thing <+>
472 hsep [ptext SLIT("is bound at stage") <+> ppr bind_lvl,
473 ptext SLIT("but used at stage") <+> ppr use_lvl]
475 use_lvl = thLevel use_stage
478 topIdLvl :: Id -> ThLevel
479 -- Globals may either be imported, or may be from an earlier "chunk"
480 -- (separated by declaration splices) of this module. The former
481 -- *can* be used inside a top-level splice, but the latter cannot.
482 -- Hence we give the former impLevel, but the latter topLevel
486 -- By the time we are prcessing the $(f x), the binding for "x"
487 -- will be in the global env, not the local one.
488 topIdLvl id | isLocalId id = topLevel
489 | otherwise = impLevel
491 -- Indicates the legal transitions on bracket( [| |] ).
492 bracketOK :: ThStage -> Maybe ThLevel
493 bracketOK (Brack _ _ _) = Nothing -- Bracket illegal inside a bracket
494 bracketOK stage = (Just (thLevel stage + 1))
496 -- Indicates the legal transitions on splice($).
497 spliceOK :: ThStage -> Maybe ThLevel
498 spliceOK (Splice _) = Nothing -- Splice illegal inside splice
499 spliceOK stage = Just (thLevel stage - 1)
501 tcMetaTy :: Name -> TcM Type
502 -- Given the name of a Template Haskell data type,
504 -- E.g. given the name "Expr" return the type "Expr"
506 = tcLookupTyCon tc_name `thenM` \ t ->
507 returnM (mkGenTyConApp t [])
508 -- Use mkGenTyConApp because it might be a synonym
512 %************************************************************************
514 \subsection{Making new Ids}
516 %************************************************************************
521 newLocalName :: Name -> TcM Name
522 newLocalName name -- Make a clone
523 = newUnique `thenM` \ uniq ->
524 returnM (mkInternalName uniq (getOccName name) (getSrcLoc name))
527 Make a name for the dict fun for an instance decl. It's a *local*
528 name for the moment. The CoreTidy pass will externalise it. Even in
529 --make and ghci stuff, we rebuild the instance environment each time,
530 so the dfun id is internal to begin with, and external when compiling
534 newDFunName :: Class -> [Type] -> SrcLoc -> TcM Name
535 newDFunName clas (ty:_) loc
536 = newUnique `thenM` \ uniq ->
537 returnM (mkInternalName uniq (mkDFunOcc dfun_string) loc)
539 -- Any string that is somewhat unique will do
540 dfun_string = occNameString (getOccName clas) ++ occNameString (getDFunTyKey ty)
542 newDFunName clas [] loc = pprPanic "newDFunName" (ppr clas <+> ppr loc)
546 %************************************************************************
548 \subsection{The InstInfo type}
550 %************************************************************************
552 The InstInfo type summarises the information in an instance declaration
554 instance c => k (t tvs) where b
556 It is used just for *local* instance decls (not ones from interface files).
557 But local instance decls includes
560 as well as explicit user written ones.
565 iDFunId :: DFunId, -- The dfun id
566 iBinds :: InstBindings
570 = VanillaInst -- The normal case
571 (LHsBinds Name) -- Bindings
572 [LSig Name] -- User pragmas recorded for generating
573 -- specialised instances
575 | NewTypeDerived -- Used for deriving instances of newtypes, where the
576 [Type] -- witness dictionary is identical to the argument
577 -- dictionary. Hence no bindings, no pragmas
578 -- The [Type] are the representation types
579 -- See notes in TcDeriv
581 pprInstInfo info = vcat [ptext SLIT("InstInfo:") <+> ppr (idType (iDFunId info))]
583 pprInstInfoDetails info = pprInstInfo info $$ nest 2 (details (iBinds info))
585 details (VanillaInst b _) = pprLHsBinds b
586 details (NewTypeDerived _) = text "Derived from the representation type"
588 simpleInstInfoTy :: InstInfo -> Type
589 simpleInstInfoTy info = case tcSplitDFunTy (idType (iDFunId info)) of
590 (_, _, _, [ty]) -> ty
592 simpleInstInfoTyCon :: InstInfo -> TyCon
593 -- Gets the type constructor for a simple instance declaration,
594 -- i.e. one of the form instance (...) => C (T a b c) where ...
595 simpleInstInfoTyCon inst = tcTyConAppTyCon (simpleInstInfoTy inst)
599 %************************************************************************
603 %************************************************************************
606 notFound wheRe name = failWithTc (text wheRe <> colon <+> quotes (ppr name) <+>
607 ptext SLIT("is not in scope"))
609 wrongThingErr expected thing name
610 = failWithTc (pp_thing thing <+> quotes (ppr name) <+>
611 ptext SLIT("used as a") <+> text expected)
613 pp_thing (AGlobal (ATyCon _)) = ptext SLIT("Type constructor")
614 pp_thing (AGlobal (AClass _)) = ptext SLIT("Class")
615 pp_thing (AGlobal (AnId _)) = ptext SLIT("Identifier")
616 pp_thing (AGlobal (ADataCon _)) = ptext SLIT("Data constructor")
617 pp_thing (ATyVar _) = ptext SLIT("Type variable")
618 pp_thing (ATcId _ _ _) = ptext SLIT("Local identifier")