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,
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, zonkTcTyVarsAndFV )
52 import TcType ( Type, TcKind, TcTyVar, TcTyVarSet, TcType,
53 tyVarsOfType, tyVarsOfTypes, tcSplitDFunTy, mkGenTyConApp,
54 getDFunTyKey, tcTyConAppTyCon, tcGetTyVar, mkTyVarTy,
55 tidyOpenType, pprTyThingCategory
57 import qualified Type ( getTyVar_maybe )
58 import Id ( idName, isLocalId )
59 import Var ( TyVar, Id, idType, tyVarName )
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 -> tcImportDecl name
113 tcLookupGlobalId :: Name -> TcM Id
114 -- Never used for Haskell-source DataCons, hence no ADataCon case
115 tcLookupGlobalId name
116 = tcLookupGlobal name `thenM` \ thing ->
117 return (tyThingId thing)
119 tcLookupDataCon :: Name -> TcM DataCon
120 tcLookupDataCon con_name
121 = tcLookupGlobal con_name `thenM` \ thing ->
122 return (tyThingDataCon thing)
124 tcLookupClass :: Name -> TcM Class
126 = tcLookupGlobal name `thenM` \ thing ->
128 AClass cls -> return cls
129 other -> wrongThingErr "class" (AGlobal thing) name
131 tcLookupTyCon :: Name -> TcM TyCon
133 = tcLookupGlobal name `thenM` \ thing ->
135 ATyCon tc -> return tc
136 other -> wrongThingErr "type constructor" (AGlobal thing) name
138 tcLookupLocatedGlobalId :: Located Name -> TcM Id
139 tcLookupLocatedGlobalId = addLocM tcLookupId
141 tcLookupLocatedClass :: Located Name -> TcM Class
142 tcLookupLocatedClass = addLocM tcLookupClass
144 tcLookupLocatedTyCon :: Located Name -> TcM TyCon
145 tcLookupLocatedTyCon = addLocM tcLookupTyCon
148 %************************************************************************
150 Extending the global environment
152 %************************************************************************
156 tcExtendGlobalEnv :: [TyThing] -> TcM r -> TcM r
157 -- Given a mixture of Ids, TyCons, Classes, all from the
158 -- module being compiled, extend the global environment
159 tcExtendGlobalEnv things thing_inside
160 = do { env <- getGblEnv
161 ; let ge' = extendTypeEnvList (tcg_type_env env) things
162 ; setGblEnv (env {tcg_type_env = ge'}) thing_inside }
164 tcExtendGlobalValEnv :: [Id] -> TcM a -> TcM a
165 -- Same deal as tcExtendGlobalEnv, but for Ids
166 tcExtendGlobalValEnv ids thing_inside
167 = tcExtendGlobalEnv [AnId id | id <- ids] thing_inside
171 tcExtendRecEnv :: [(Name,TyThing)] -> TcM r -> TcM r
172 -- Extend the global environments for the type/class knot tying game
173 tcExtendRecEnv gbl_stuff thing_inside
174 = updGblEnv upd thing_inside
176 upd env = env { tcg_type_env = extend (tcg_type_env env) }
177 extend env = extendNameEnvList env gbl_stuff
181 %************************************************************************
183 \subsection{The local environment}
185 %************************************************************************
188 tcLookupLocated :: Located Name -> TcM TcTyThing
189 tcLookupLocated = addLocM tcLookup
191 tcLookup :: Name -> TcM TcTyThing
193 = getLclEnv `thenM` \ local_env ->
194 case lookupNameEnv (tcl_env local_env) name of
195 Just thing -> returnM thing
196 Nothing -> tcLookupGlobal name `thenM` \ thing ->
197 returnM (AGlobal thing)
199 tcLookupTyVar :: Name -> TcM TcTyVar
201 = tcLookup name `thenM` \ thing ->
203 ATyVar _ ty -> returnM (tcGetTyVar "tcLookupTyVar" ty)
204 other -> pprPanic "tcLookupTyVar" (ppr name)
206 tcLookupId :: Name -> TcM Id
207 -- Used when we aren't interested in the binding level
208 -- Never a DataCon. (Why does that matter? see TcExpr.tcId)
210 = tcLookup name `thenM` \ thing ->
212 ATcId tc_id _ _ -> returnM tc_id
213 AGlobal (AnId id) -> returnM id
214 other -> pprPanic "tcLookupId" (ppr name)
216 tcLookupLocalIds :: [Name] -> TcM [TcId]
217 -- We expect the variables to all be bound, and all at
218 -- the same level as the lookup. Only used in one place...
220 = getLclEnv `thenM` \ env ->
221 returnM (map (lookup (tcl_env env) (thLevel (tcl_th_ctxt env))) ns)
224 = case lookupNameEnv lenv name of
225 Just (ATcId id lvl1 _) -> ASSERT( lvl == lvl1 ) id
226 other -> pprPanic "tcLookupLocalIds" (ppr name)
228 lclEnvElts :: TcLclEnv -> [TcTyThing]
229 lclEnvElts env = nameEnvElts (tcl_env env)
231 getInLocalScope :: TcM (Name -> Bool)
233 getInLocalScope = getLclEnv `thenM` \ env ->
235 lcl_env = tcl_env env
237 return (`elemNameEnv` lcl_env)
241 tcExtendKindEnv :: [(Name, TcKind)] -> TcM r -> TcM r
242 tcExtendKindEnv things thing_inside
243 = updLclEnv upd thing_inside
245 upd lcl_env = lcl_env { tcl_env = extend (tcl_env lcl_env) }
246 extend env = extendNameEnvList env [(n, AThing k) | (n,k) <- things]
248 tcExtendTyVarEnv :: [TyVar] -> TcM r -> TcM r
249 tcExtendTyVarEnv tvs thing_inside
250 = tcExtendTyVarEnv2 [(tyVarName tv, mkTyVarTy tv) | tv <- tvs] thing_inside
252 tcExtendTyVarEnv2 :: [(Name,TcType)] -> TcM r -> TcM r
253 tcExtendTyVarEnv2 binds thing_inside
254 = getLclEnv `thenM` \ env@(TcLclEnv {tcl_env = le,
256 tcl_rdr = rdr_env}) ->
258 rdr_env' = extendLocalRdrEnv rdr_env (map fst binds)
259 new_tv_set = tyVarsOfTypes (map snd binds)
260 le' = extendNameEnvList le [(name, ATyVar name ty) | (name, ty) <- binds]
262 -- It's important to add the in-scope tyvars to the global tyvar set
264 -- f (_::r) = let g y = y::r in ...
265 -- Here, g mustn't be generalised. This is also important during
266 -- class and instance decls, when we mustn't generalise the class tyvars
267 -- when typechecking the methods.
268 tc_extend_gtvs gtvs new_tv_set `thenM` \ gtvs' ->
269 setLclEnv (env {tcl_env = le', tcl_tyvars = gtvs', tcl_rdr = rdr_env'}) thing_inside
274 tcExtendIdEnv :: [TcId] -> TcM a -> TcM a
275 -- Invariant: the TcIds are fully zonked. Reasons:
276 -- (a) The kinds of the forall'd type variables are defaulted
277 -- (see Kind.defaultKind, done in zonkQuantifiedTyVar)
278 -- (b) There are no via-Indirect occurrences of the bound variables
279 -- in the types, because instantiation does not look through such things
280 -- (c) The call to tyVarsOfTypes is ok without looking through refs
281 tcExtendIdEnv ids thing_inside = tcExtendIdEnv2 [(idName id, id) | id <- ids] thing_inside
283 tcExtendIdEnv1 :: Name -> TcId -> TcM a -> TcM a
284 tcExtendIdEnv1 name id thing_inside = tcExtendIdEnv2 [(name,id)] thing_inside
286 tcExtendIdEnv2 :: [(Name,TcId)] -> TcM a -> TcM a
287 -- Invariant: the TcIds are fully zonked (see tcExtendIdEnv above)
288 tcExtendIdEnv2 names_w_ids thing_inside
289 = getLclEnv `thenM` \ env ->
291 extra_global_tyvars = tyVarsOfTypes [idType id | (name,id) <- names_w_ids]
292 th_lvl = thLevel (tcl_th_ctxt env)
293 proc_lvl = proc_level (tcl_arrow_ctxt env)
294 extra_env = [(name, ATcId id th_lvl proc_lvl) | (name,id) <- names_w_ids]
295 le' = extendNameEnvList (tcl_env env) extra_env
296 rdr_env' = extendLocalRdrEnv (tcl_rdr env) (map fst names_w_ids)
298 tc_extend_gtvs (tcl_tyvars env) extra_global_tyvars `thenM` \ gtvs' ->
299 setLclEnv (env {tcl_env = le', tcl_tyvars = gtvs', tcl_rdr = rdr_env'}) thing_inside
304 -----------------------
305 -- findGlobals looks at the value environment and finds values
306 -- whose types mention the offending type variable. It has to be
307 -- careful to zonk the Id's type first, so it has to be in the monad.
308 -- We must be careful to pass it a zonked type variable, too.
310 findGlobals :: TcTyVarSet
312 -> TcM (TidyEnv, [SDoc])
314 findGlobals tvs tidy_env
315 = getLclEnv `thenM` \ lcl_env ->
316 go tidy_env [] (lclEnvElts lcl_env)
318 go tidy_env acc [] = returnM (tidy_env, acc)
319 go tidy_env acc (thing : things)
320 = find_thing ignore_it tidy_env thing `thenM` \ (tidy_env1, maybe_doc) ->
322 Just d -> go tidy_env1 (d:acc) things
323 Nothing -> go tidy_env1 acc things
325 ignore_it ty = not (tvs `intersectsVarSet` tyVarsOfType ty)
327 -----------------------
328 find_thing ignore_it tidy_env (ATcId id _ _)
329 = zonkTcType (idType id) `thenM` \ id_ty ->
330 if ignore_it id_ty then
331 returnM (tidy_env, Nothing)
333 (tidy_env', tidy_ty) = tidyOpenType tidy_env id_ty
334 msg = sep [ppr id <+> dcolon <+> ppr tidy_ty,
335 nest 2 (parens (ptext SLIT("bound at") <+>
336 ppr (getSrcLoc id)))]
338 returnM (tidy_env', Just msg)
340 find_thing ignore_it tidy_env (ATyVar tv ty)
341 = zonkTcType ty `thenM` \ tv_ty ->
342 if ignore_it tv_ty then
343 returnM (tidy_env, Nothing)
345 -- The name tv is scoped, so we don't need to tidy it
346 (tidy_env1, tidy_ty) = tidyOpenType tidy_env tv_ty
347 msg = sep [ppr tv <+> eq_stuff, nest 2 bound_at]
349 eq_stuff | Just tv' <- Type.getTyVar_maybe tv_ty,
350 tv == tyVarName tv' = empty
351 | otherwise = equals <+> ppr tidy_ty
352 -- It's ok to use Type.getTyVar_maybe because ty is zonked by now
353 bound_at = ptext SLIT("bound at:") <+> ppr (getSrcLoc tv)
355 returnM (tidy_env1, Just msg)
359 %************************************************************************
361 \subsection{The global tyvars}
363 %************************************************************************
366 tc_extend_gtvs gtvs extra_global_tvs
367 = readMutVar gtvs `thenM` \ global_tvs ->
368 newMutVar (global_tvs `unionVarSet` extra_global_tvs)
371 @tcGetGlobalTyVars@ returns a fully-zonked set of tyvars free in the environment.
372 To improve subsequent calls to the same function it writes the zonked set back into
376 tcGetGlobalTyVars :: TcM TcTyVarSet
378 = getLclEnv `thenM` \ (TcLclEnv {tcl_tyvars = gtv_var}) ->
379 readMutVar gtv_var `thenM` \ gbl_tvs ->
380 zonkTcTyVarsAndFV (varSetElems gbl_tvs) `thenM` \ gbl_tvs' ->
381 writeMutVar gtv_var gbl_tvs' `thenM_`
386 %************************************************************************
390 %************************************************************************
393 tcExtendRules :: [LRuleDecl Id] -> TcM a -> TcM a
394 -- Just pop the new rules into the EPS and envt resp
395 -- All the rules come from an interface file, not soruce
396 -- Nevertheless, some may be for this module, if we read
397 -- its interface instead of its source code
398 tcExtendRules lcl_rules thing_inside
399 = do { env <- getGblEnv
401 env' = env { tcg_rules = lcl_rules ++ tcg_rules env }
402 ; setGblEnv env' thing_inside }
406 %************************************************************************
408 Arrow notation proc levels
410 %************************************************************************
413 checkProcLevel :: TcId -> ProcLevel -> TcM ()
414 checkProcLevel id id_lvl
415 = do { banned <- getBannedProcLevels
416 ; checkTc (not (id_lvl `elem` banned))
417 (procLevelErr id id_lvl) }
419 procLevelErr id id_lvl
420 = hang (ptext SLIT("Command-bound variable") <+> quotes (ppr id) <+> ptext SLIT("is not in scope here"))
421 4 (ptext SLIT("Reason: it is used in the left argument of (-<)"))
425 %************************************************************************
429 %************************************************************************
432 instance Outputable ThStage where
433 ppr Comp = text "Comp"
434 ppr (Brack l _ _) = text "Brack" <+> int l
435 ppr (Splice l) = text "Splice" <+> int l
438 thLevel :: ThStage -> ThLevel
439 thLevel Comp = topLevel
440 thLevel (Splice l) = l
441 thLevel (Brack l _ _) = l
444 checkWellStaged :: SDoc -- What the stage check is for
445 -> ThLevel -- Binding level
446 -> ThStage -- Use stage
447 -> TcM () -- Fail if badly staged, adding an error
448 checkWellStaged pp_thing bind_lvl use_stage
449 | bind_lvl <= use_lvl -- OK!
452 | bind_lvl == topLevel -- GHC restriction on top level splices
454 sep [ptext SLIT("GHC stage restriction:") <+> pp_thing,
455 nest 2 (ptext SLIT("is used in a top-level splice, and must be imported, not defined locally"))]
457 | otherwise -- Badly staged
459 ptext SLIT("Stage error:") <+> pp_thing <+>
460 hsep [ptext SLIT("is bound at stage") <+> ppr bind_lvl,
461 ptext SLIT("but used at stage") <+> ppr use_lvl]
463 use_lvl = thLevel use_stage
466 topIdLvl :: Id -> ThLevel
467 -- Globals may either be imported, or may be from an earlier "chunk"
468 -- (separated by declaration splices) of this module. The former
469 -- *can* be used inside a top-level splice, but the latter cannot.
470 -- Hence we give the former impLevel, but the latter topLevel
474 -- By the time we are prcessing the $(f x), the binding for "x"
475 -- will be in the global env, not the local one.
476 topIdLvl id | isLocalId id = topLevel
477 | otherwise = impLevel
479 -- Indicates the legal transitions on bracket( [| |] ).
480 bracketOK :: ThStage -> Maybe ThLevel
481 bracketOK (Brack _ _ _) = Nothing -- Bracket illegal inside a bracket
482 bracketOK stage = Just (thLevel stage + 1)
484 -- Indicates the legal transitions on splice($).
485 spliceOK :: ThStage -> Maybe ThLevel
486 spliceOK (Splice _) = Nothing -- Splice illegal inside splice
487 spliceOK stage = Just (thLevel stage - 1)
489 tcMetaTy :: Name -> TcM Type
490 -- Given the name of a Template Haskell data type,
492 -- E.g. given the name "Expr" return the type "Expr"
494 = tcLookupTyCon tc_name `thenM` \ t ->
495 returnM (mkGenTyConApp t [])
496 -- Use mkGenTyConApp because it might be a synonym
500 %************************************************************************
502 \subsection{Making new Ids}
504 %************************************************************************
509 newLocalName :: Name -> TcM Name
510 newLocalName name -- Make a clone
511 = newUnique `thenM` \ uniq ->
512 returnM (mkInternalName uniq (getOccName name) (getSrcLoc name))
515 Make a name for the dict fun for an instance decl. It's a *local*
516 name for the moment. The CoreTidy pass will externalise it. Even in
517 --make and ghci stuff, we rebuild the instance environment each time,
518 so the dfun id is internal to begin with, and external when compiling
522 newDFunName :: Class -> [Type] -> SrcLoc -> TcM Name
523 newDFunName clas (ty:_) loc
524 = newUnique `thenM` \ uniq ->
525 returnM (mkInternalName uniq (mkDFunOcc dfun_string) loc)
527 -- Any string that is somewhat unique will do
528 dfun_string = occNameString (getOccName clas) ++ occNameString (getDFunTyKey ty)
530 newDFunName clas [] loc = pprPanic "newDFunName" (ppr clas <+> ppr loc)
534 %************************************************************************
536 \subsection{The InstInfo type}
538 %************************************************************************
540 The InstInfo type summarises the information in an instance declaration
542 instance c => k (t tvs) where b
544 It is used just for *local* instance decls (not ones from interface files).
545 But local instance decls includes
548 as well as explicit user written ones.
553 iDFunId :: DFunId, -- The dfun id. Its forall'd type variables
554 iBinds :: InstBindings -- scope over the stuff in InstBindings!
558 = VanillaInst -- The normal case
559 (LHsBinds Name) -- Bindings
560 [LSig Name] -- User pragmas recorded for generating
561 -- specialised instances
563 | NewTypeDerived -- Used for deriving instances of newtypes, where the
564 [Type] -- witness dictionary is identical to the argument
565 -- dictionary. Hence no bindings, no pragmas
566 -- The [Type] are the representation types
567 -- See notes in TcDeriv
569 pprInstInfo info = vcat [ptext SLIT("InstInfo:") <+> ppr (idType (iDFunId info))]
571 pprInstInfoDetails info = pprInstInfo info $$ nest 2 (details (iBinds info))
573 details (VanillaInst b _) = pprLHsBinds b
574 details (NewTypeDerived _) = text "Derived from the representation type"
576 simpleInstInfoTy :: InstInfo -> Type
577 simpleInstInfoTy info = case tcSplitDFunTy (idType (iDFunId info)) of
578 (_, _, _, [ty]) -> ty
580 simpleInstInfoTyCon :: InstInfo -> TyCon
581 -- Gets the type constructor for a simple instance declaration,
582 -- i.e. one of the form instance (...) => C (T a b c) where ...
583 simpleInstInfoTyCon inst = tcTyConAppTyCon (simpleInstInfoTy inst)
587 %************************************************************************
591 %************************************************************************
595 = failWithTc (ptext SLIT("GHC internal error:") <+> quotes (ppr name) <+>
596 ptext SLIT("is not in scope"))
598 wrongThingErr expected thing name
599 = failWithTc (pp_thing thing <+> quotes (ppr name) <+>
600 ptext SLIT("used as a") <+> text expected)
602 pp_thing (AGlobal thing) = pprTyThingCategory thing
603 pp_thing (ATyVar _ _) = ptext SLIT("Type variable")
604 pp_thing (ATcId _ _ _) = ptext SLIT("Local identifier")