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,
20 tcExtendTyVarEnv, tcExtendTyVarEnv2, tcExtendTyVarEnv3,
21 tcExtendIdEnv, tcExtendIdEnv1, tcExtendIdEnv2,
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, TcType,
53 tyVarsOfType, tyVarsOfTypes, tcSplitDFunTy, mkGenTyConApp,
54 getDFunTyKey, tcTyConAppTyCon, tcGetTyVar, mkTyVarTy,
55 tidyOpenType, tidyOpenTyVar, pprTyThingCategory
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(..) )
78 %************************************************************************
82 %************************************************************************
84 Using the Located versions (eg. tcLookupLocatedGlobal) is preferred,
85 unless you know that the SrcSpan in the monad is already set to the
89 tcLookupLocatedGlobal :: Located Name -> TcM TyThing
90 -- c.f. IfaceEnvEnv.tcIfaceGlobal
91 tcLookupLocatedGlobal name
92 = addLocM tcLookupGlobal name
94 tcLookupGlobal :: Name -> TcM TyThing
96 = do { env <- getGblEnv
97 ; if nameIsLocalOrFrom (tcg_mod env) name
99 then -- It's defined in this module
100 case lookupNameEnv (tcg_type_env env) name of
101 Just thing -> return thing
102 Nothing -> notFound name -- Panic!
104 else do -- It's imported
105 { (eps,hpt) <- getEpsAndHpt
106 ; case lookupType hpt (eps_PTE eps) name of
107 Just thing -> return thing
108 Nothing -> do { traceIf (text "tcLookupGlobal" <+> ppr name)
109 ; initIfaceTcRn (tcImportDecl name) }
114 tcLookupGlobalId :: Name -> TcM Id
115 -- Never used for Haskell-source DataCons, hence no ADataCon case
116 tcLookupGlobalId name
117 = tcLookupGlobal name `thenM` \ thing ->
118 return (tyThingId thing)
120 tcLookupDataCon :: Name -> TcM DataCon
121 tcLookupDataCon con_name
122 = tcLookupGlobal con_name `thenM` \ thing ->
123 return (tyThingDataCon thing)
125 tcLookupClass :: Name -> TcM Class
127 = tcLookupGlobal name `thenM` \ thing ->
129 AClass cls -> return cls
130 other -> wrongThingErr "class" (AGlobal thing) name
132 tcLookupTyCon :: Name -> TcM TyCon
134 = tcLookupGlobal name `thenM` \ thing ->
136 ATyCon tc -> return tc
137 other -> wrongThingErr "type constructor" (AGlobal thing) name
139 tcLookupLocatedGlobalId :: Located Name -> TcM Id
140 tcLookupLocatedGlobalId = addLocM tcLookupId
142 tcLookupLocatedClass :: Located Name -> TcM Class
143 tcLookupLocatedClass = addLocM tcLookupClass
145 tcLookupLocatedTyCon :: Located Name -> TcM TyCon
146 tcLookupLocatedTyCon = addLocM tcLookupTyCon
149 %************************************************************************
151 Extending the global environment
153 %************************************************************************
157 tcExtendGlobalEnv :: [TyThing] -> TcM r -> TcM r
158 -- Given a mixture of Ids, TyCons, Classes, all from the
159 -- module being compiled, extend the global environment
160 tcExtendGlobalEnv things thing_inside
161 = do { env <- getGblEnv
162 ; let ge' = extendTypeEnvList (tcg_type_env env) things
163 ; setGblEnv (env {tcg_type_env = ge'}) thing_inside }
165 tcExtendGlobalValEnv :: [Id] -> TcM a -> TcM a
166 -- Same deal as tcExtendGlobalEnv, but for Ids
167 tcExtendGlobalValEnv ids thing_inside
168 = tcExtendGlobalEnv [AnId id | id <- ids] thing_inside
172 tcExtendRecEnv :: [(Name,TyThing)] -> TcM r -> TcM r
173 -- Extend the global environments for the type/class knot tying game
174 tcExtendRecEnv gbl_stuff thing_inside
175 = updGblEnv upd thing_inside
177 upd env = env { tcg_type_env = extend (tcg_type_env env) }
178 extend env = extendNameEnvList env gbl_stuff
182 %************************************************************************
184 \subsection{The local environment}
186 %************************************************************************
189 tcLookupLocated :: Located Name -> TcM TcTyThing
190 tcLookupLocated = addLocM tcLookup
192 tcLookup :: Name -> TcM TcTyThing
194 = getLclEnv `thenM` \ local_env ->
195 case lookupNameEnv (tcl_env local_env) name of
196 Just thing -> returnM thing
197 Nothing -> tcLookupGlobal name `thenM` \ thing ->
198 returnM (AGlobal thing)
200 tcLookupTyVar :: Name -> TcM TcTyVar
202 = tcLookup name `thenM` \ thing ->
204 ATyVar _ ty -> returnM (tcGetTyVar "tcLookupTyVar" ty)
205 other -> pprPanic "tcLookupTyVar" (ppr name)
207 tcLookupId :: Name -> TcM Id
208 -- Used when we aren't interested in the binding level
209 -- Never a DataCon. (Why does that matter? see TcExpr.tcId)
211 = tcLookup name `thenM` \ thing ->
213 ATcId tc_id _ _ -> returnM tc_id
214 AGlobal (AnId id) -> returnM id
215 other -> pprPanic "tcLookupId" (ppr name)
217 tcLookupLocalIds :: [Name] -> TcM [TcId]
218 -- We expect the variables to all be bound, and all at
219 -- the same level as the lookup. Only used in one place...
221 = getLclEnv `thenM` \ env ->
222 returnM (map (lookup (tcl_env env) (thLevel (tcl_th_ctxt env))) ns)
225 = case lookupNameEnv lenv name of
226 Just (ATcId id lvl1 _) -> ASSERT( lvl == lvl1 ) id
227 other -> pprPanic "tcLookupLocalIds" (ppr name)
229 lclEnvElts :: TcLclEnv -> [TcTyThing]
230 lclEnvElts env = nameEnvElts (tcl_env env)
232 getInLocalScope :: TcM (Name -> Bool)
234 getInLocalScope = getLclEnv `thenM` \ env ->
236 lcl_env = tcl_env env
238 return (`elemNameEnv` lcl_env)
242 tcExtendKindEnv :: [(Name, TcKind)] -> TcM r -> TcM r
243 tcExtendKindEnv things thing_inside
244 = updLclEnv upd thing_inside
246 upd lcl_env = lcl_env { tcl_env = extend (tcl_env lcl_env) }
247 extend env = extendNameEnvList env [(n, AThing k) | (n,k) <- things]
249 tcExtendTyVarEnv :: [TyVar] -> TcM r -> TcM r
250 tcExtendTyVarEnv tvs thing_inside
251 = tc_extend_tv_env [ATyVar tv (mkTyVarTy tv) | tv <- tvs] thing_inside
253 tcExtendTyVarEnv2 :: [(TyVar,TcTyVar)] -> TcM r -> TcM r
254 tcExtendTyVarEnv2 tv_pairs thing_inside
255 = tc_extend_tv_env [ATyVar tv1 (mkTyVarTy tv2) | (tv1,tv2) <- tv_pairs] thing_inside
257 tcExtendTyVarEnv3 :: [(TyVar,TcType)] -> TcM r -> TcM r
258 tcExtendTyVarEnv3 ty_pairs thing_inside
259 = tc_extend_tv_env [ATyVar tv1 ty2 | (tv1,ty2) <- ty_pairs] thing_inside
261 tc_extend_tv_env binds thing_inside
262 = getLclEnv `thenM` \ env@(TcLclEnv {tcl_env = le,
264 tcl_rdr = rdr_env}) ->
266 names = [getName tv | ATyVar tv _ <- binds]
267 rdr_env' = extendLocalRdrEnv rdr_env names
268 le' = extendNameEnvList le (names `zip` binds)
269 new_tv_set = tyVarsOfTypes [ty | ATyVar _ ty <- binds]
271 -- It's important to add the in-scope tyvars to the global tyvar set
273 -- f (_::r) = let g y = y::r in ...
274 -- Here, g mustn't be generalised. This is also important during
275 -- class and instance decls, when we mustn't generalise the class tyvars
276 -- when typechecking the methods.
277 tc_extend_gtvs gtvs new_tv_set `thenM` \ gtvs' ->
278 setLclEnv (env {tcl_env = le', tcl_tyvars = gtvs', tcl_rdr = rdr_env'}) thing_inside
283 tcExtendIdEnv :: [TcId] -> TcM a -> TcM a
284 -- Invariant: the TcIds are fully zonked. Reasons:
285 -- (a) The kinds of the forall'd type variables are defaulted
286 -- (see Kind.defaultKind, done in zonkQuantifiedTyVar)
287 -- (b) There are no via-Indirect occurrences of the bound variables
288 -- in the types, because instantiation does not look through such things
289 -- (c) The call to tyVarsOfTypes is ok without looking through refs
290 tcExtendIdEnv ids thing_inside = tcExtendIdEnv2 [(idName id, id) | id <- ids] thing_inside
292 tcExtendIdEnv1 :: Name -> TcId -> TcM a -> TcM a
293 tcExtendIdEnv1 name id thing_inside = tcExtendIdEnv2 [(name,id)] thing_inside
295 tcExtendIdEnv2 :: [(Name,TcId)] -> TcM a -> TcM a
296 -- Invariant: the TcIds are fully zonked (see tcExtendIdEnv above)
297 tcExtendIdEnv2 names_w_ids thing_inside
298 = getLclEnv `thenM` \ env ->
300 extra_global_tyvars = tyVarsOfTypes [idType id | (name,id) <- names_w_ids]
301 th_lvl = thLevel (tcl_th_ctxt env)
302 proc_lvl = proc_level (tcl_arrow_ctxt env)
303 extra_env = [(name, ATcId id th_lvl proc_lvl) | (name,id) <- names_w_ids]
304 le' = extendNameEnvList (tcl_env env) extra_env
305 rdr_env' = extendLocalRdrEnv (tcl_rdr env) (map fst names_w_ids)
307 tc_extend_gtvs (tcl_tyvars env) extra_global_tyvars `thenM` \ gtvs' ->
308 setLclEnv (env {tcl_env = le', tcl_tyvars = gtvs', tcl_rdr = rdr_env'}) thing_inside
313 -----------------------
314 -- findGlobals looks at the value environment and finds values
315 -- whose types mention the offending type variable. It has to be
316 -- careful to zonk the Id's type first, so it has to be in the monad.
317 -- We must be careful to pass it a zonked type variable, too.
319 findGlobals :: TcTyVarSet
321 -> TcM (TidyEnv, [SDoc])
323 findGlobals tvs tidy_env
324 = getLclEnv `thenM` \ lcl_env ->
325 go tidy_env [] (lclEnvElts lcl_env)
327 go tidy_env acc [] = returnM (tidy_env, acc)
328 go tidy_env acc (thing : things)
329 = find_thing ignore_it tidy_env thing `thenM` \ (tidy_env1, maybe_doc) ->
331 Just d -> go tidy_env1 (d:acc) things
332 Nothing -> go tidy_env1 acc things
334 ignore_it ty = not (tvs `intersectsVarSet` tyVarsOfType ty)
336 -----------------------
337 find_thing ignore_it tidy_env (ATcId id _ _)
338 = zonkTcType (idType id) `thenM` \ id_ty ->
339 if ignore_it id_ty then
340 returnM (tidy_env, Nothing)
342 (tidy_env', tidy_ty) = tidyOpenType tidy_env id_ty
343 msg = sep [ppr id <+> dcolon <+> ppr tidy_ty,
344 nest 2 (parens (ptext SLIT("bound at") <+>
345 ppr (getSrcLoc id)))]
347 returnM (tidy_env', Just msg)
349 find_thing ignore_it tidy_env (ATyVar tv ty)
350 = zonkTcType ty `thenM` \ tv_ty ->
351 if ignore_it tv_ty then
352 returnM (tidy_env, Nothing)
354 (tidy_env1, tv1) = tidyOpenTyVar tidy_env tv
355 (tidy_env2, tidy_ty) = tidyOpenType tidy_env1 tv_ty
356 msg = sep [ppr tv1 <+> eq_stuff, nest 2 bound_at]
358 eq_stuff | Just tv' <- Type.getTyVar_maybe tv_ty,
360 | otherwise = equals <+> ppr tidy_ty
361 -- It's ok to use Type.getTyVar_maybe because ty is zonked by now
362 bound_at = ptext SLIT("bound at:") <+> ppr (getSrcLoc tv)
364 returnM (tidy_env2, Just msg)
368 %************************************************************************
370 \subsection{The global tyvars}
372 %************************************************************************
375 tc_extend_gtvs gtvs extra_global_tvs
376 = readMutVar gtvs `thenM` \ global_tvs ->
377 newMutVar (global_tvs `unionVarSet` extra_global_tvs)
380 @tcGetGlobalTyVars@ returns a fully-zonked set of tyvars free in the environment.
381 To improve subsequent calls to the same function it writes the zonked set back into
385 tcGetGlobalTyVars :: TcM TcTyVarSet
387 = getLclEnv `thenM` \ (TcLclEnv {tcl_tyvars = gtv_var}) ->
388 readMutVar gtv_var `thenM` \ gbl_tvs ->
389 zonkTcTyVarsAndFV (varSetElems gbl_tvs) `thenM` \ gbl_tvs' ->
390 writeMutVar gtv_var gbl_tvs' `thenM_`
395 %************************************************************************
399 %************************************************************************
402 tcExtendRules :: [LRuleDecl Id] -> TcM a -> TcM a
403 -- Just pop the new rules into the EPS and envt resp
404 -- All the rules come from an interface file, not soruce
405 -- Nevertheless, some may be for this module, if we read
406 -- its interface instead of its source code
407 tcExtendRules lcl_rules thing_inside
408 = do { env <- getGblEnv
410 env' = env { tcg_rules = lcl_rules ++ tcg_rules env }
411 ; setGblEnv env' thing_inside }
415 %************************************************************************
417 Arrow notation proc levels
419 %************************************************************************
422 checkProcLevel :: TcId -> ProcLevel -> TcM ()
423 checkProcLevel id id_lvl
424 = do { banned <- getBannedProcLevels
425 ; checkTc (not (id_lvl `elem` banned))
426 (procLevelErr id id_lvl) }
428 procLevelErr id id_lvl
429 = hang (ptext SLIT("Command-bound variable") <+> quotes (ppr id) <+> ptext SLIT("is not in scope here"))
430 4 (ptext SLIT("Reason: it is used in the left argument of (-<)"))
434 %************************************************************************
438 %************************************************************************
441 instance Outputable ThStage where
442 ppr Comp = text "Comp"
443 ppr (Brack l _ _) = text "Brack" <+> int l
444 ppr (Splice l) = text "Splice" <+> int l
447 thLevel :: ThStage -> ThLevel
448 thLevel Comp = topLevel
449 thLevel (Splice l) = l
450 thLevel (Brack l _ _) = l
453 checkWellStaged :: SDoc -- What the stage check is for
454 -> ThLevel -- Binding level
455 -> ThStage -- Use stage
456 -> TcM () -- Fail if badly staged, adding an error
457 checkWellStaged pp_thing bind_lvl use_stage
458 | bind_lvl <= use_lvl -- OK!
461 | bind_lvl == topLevel -- GHC restriction on top level splices
463 sep [ptext SLIT("GHC stage restriction:") <+> pp_thing,
464 nest 2 (ptext SLIT("is used in a top-level splice, and must be imported, not defined locally"))]
466 | otherwise -- Badly staged
468 ptext SLIT("Stage error:") <+> pp_thing <+>
469 hsep [ptext SLIT("is bound at stage") <+> ppr bind_lvl,
470 ptext SLIT("but used at stage") <+> ppr use_lvl]
472 use_lvl = thLevel use_stage
475 topIdLvl :: Id -> ThLevel
476 -- Globals may either be imported, or may be from an earlier "chunk"
477 -- (separated by declaration splices) of this module. The former
478 -- *can* be used inside a top-level splice, but the latter cannot.
479 -- Hence we give the former impLevel, but the latter topLevel
483 -- By the time we are prcessing the $(f x), the binding for "x"
484 -- will be in the global env, not the local one.
485 topIdLvl id | isLocalId id = topLevel
486 | otherwise = impLevel
488 -- Indicates the legal transitions on bracket( [| |] ).
489 bracketOK :: ThStage -> Maybe ThLevel
490 bracketOK (Brack _ _ _) = Nothing -- Bracket illegal inside a bracket
491 bracketOK stage = Just (thLevel stage + 1)
493 -- Indicates the legal transitions on splice($).
494 spliceOK :: ThStage -> Maybe ThLevel
495 spliceOK (Splice _) = Nothing -- Splice illegal inside splice
496 spliceOK stage = Just (thLevel stage - 1)
498 tcMetaTy :: Name -> TcM Type
499 -- Given the name of a Template Haskell data type,
501 -- E.g. given the name "Expr" return the type "Expr"
503 = tcLookupTyCon tc_name `thenM` \ t ->
504 returnM (mkGenTyConApp t [])
505 -- Use mkGenTyConApp because it might be a synonym
509 %************************************************************************
511 \subsection{Making new Ids}
513 %************************************************************************
518 newLocalName :: Name -> TcM Name
519 newLocalName name -- Make a clone
520 = newUnique `thenM` \ uniq ->
521 returnM (mkInternalName uniq (getOccName name) (getSrcLoc name))
524 Make a name for the dict fun for an instance decl. It's a *local*
525 name for the moment. The CoreTidy pass will externalise it. Even in
526 --make and ghci stuff, we rebuild the instance environment each time,
527 so the dfun id is internal to begin with, and external when compiling
531 newDFunName :: Class -> [Type] -> SrcLoc -> TcM Name
532 newDFunName clas (ty:_) loc
533 = newUnique `thenM` \ uniq ->
534 returnM (mkInternalName uniq (mkDFunOcc dfun_string) loc)
536 -- Any string that is somewhat unique will do
537 dfun_string = occNameString (getOccName clas) ++ occNameString (getDFunTyKey ty)
539 newDFunName clas [] loc = pprPanic "newDFunName" (ppr clas <+> ppr loc)
543 %************************************************************************
545 \subsection{The InstInfo type}
547 %************************************************************************
549 The InstInfo type summarises the information in an instance declaration
551 instance c => k (t tvs) where b
553 It is used just for *local* instance decls (not ones from interface files).
554 But local instance decls includes
557 as well as explicit user written ones.
562 iDFunId :: DFunId, -- The dfun id
563 iBinds :: InstBindings
567 = VanillaInst -- The normal case
568 (LHsBinds Name) -- Bindings
569 [LSig Name] -- User pragmas recorded for generating
570 -- specialised instances
572 | NewTypeDerived -- Used for deriving instances of newtypes, where the
573 [Type] -- witness dictionary is identical to the argument
574 -- dictionary. Hence no bindings, no pragmas
575 -- The [Type] are the representation types
576 -- See notes in TcDeriv
578 pprInstInfo info = vcat [ptext SLIT("InstInfo:") <+> ppr (idType (iDFunId info))]
580 pprInstInfoDetails info = pprInstInfo info $$ nest 2 (details (iBinds info))
582 details (VanillaInst b _) = pprLHsBinds b
583 details (NewTypeDerived _) = text "Derived from the representation type"
585 simpleInstInfoTy :: InstInfo -> Type
586 simpleInstInfoTy info = case tcSplitDFunTy (idType (iDFunId info)) of
587 (_, _, _, [ty]) -> ty
589 simpleInstInfoTyCon :: InstInfo -> TyCon
590 -- Gets the type constructor for a simple instance declaration,
591 -- i.e. one of the form instance (...) => C (T a b c) where ...
592 simpleInstInfoTyCon inst = tcTyConAppTyCon (simpleInstInfoTy inst)
596 %************************************************************************
600 %************************************************************************
604 = failWithTc (ptext SLIT("GHC internal error:") <+> quotes (ppr name) <+>
605 ptext SLIT("is not in scope"))
607 wrongThingErr expected thing name
608 = failWithTc (pp_thing thing <+> quotes (ppr name) <+>
609 ptext SLIT("used as a") <+> text expected)
611 pp_thing (AGlobal thing) = pprTyThingCategory thing
612 pp_thing (ATyVar _ _) = ptext SLIT("Type variable")
613 pp_thing (ATcId _ _ _) = ptext SLIT("Local identifier")