X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcEnv.lhs;h=c08e43b8382f018151bed931952b0f4a756b52b6;hb=979947f545d70c63edb7ca96f6e47008ac90e3bf;hp=b1fd6398b889c276de41d93c64950528e165dadd;hpb=e73218c6a995e56a60eab34594802d6a1067a604;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/TcEnv.lhs b/ghc/compiler/typecheck/TcEnv.lhs index b1fd639..c08e43b 100644 --- a/ghc/compiler/typecheck/TcEnv.lhs +++ b/ghc/compiler/typecheck/TcEnv.lhs @@ -1,255 +1,396 @@ \begin{code} module TcEnv( - TcId, TcIdSet, tcInstId, - tcLookupDataCon, + TcId, TcIdSet, + TyThing(..), TyThingDetails(..), TcTyThing(..), - TcEnv, ValueEnv, TyThing(..), TyThingDetails(..), tyThingKind, - - initEnv, getEnvTyCons, getEnvClasses, + -- Getting stuff from the environment + TcEnv, initTcEnv, + tcEnvTyCons, tcEnvClasses, tcEnvIds, tcLEnvElts, + getTcGEnv, - tcExtendUVarEnv, tcLookupUVar, - - tcExtendKindEnv, tcExtendTyVarEnv, - tcExtendTyVarEnvForMeths, tcExtendTypeEnv, tcGetInScopeTyVars, - - tcLookupTy, - tcLookupTyConByKey, - tcLookupClassByKey, tcLookupClassByKey_maybe, - - tcExtendGlobalValEnv, tcExtendLocalValEnv, - tcGetValueEnv, tcSetValueEnv, - tcAddImportedIdInfo, - - tcLookupValue, tcLookupValueMaybe, - tcLookupValueByKey, tcLookupValueByKeyMaybe, - explicitLookupValueByKey, explicitLookupValue, - valueEnvIds, - - newLocalId, newSpecPragmaId, - newDefaultMethodName, newDFunName, + -- Instance environment, and InstInfo type + tcGetInstEnv, tcSetInstEnv, + InstInfo(..), pprInstInfo, + simpleInstInfoTy, simpleInstInfoTyCon, + + -- Global environment + tcExtendGlobalEnv, tcExtendGlobalValEnv, tcExtendGlobalTypeEnv, + tcLookupTyCon, tcLookupClass, tcLookupGlobalId, tcLookupDataCon, + tcLookupGlobal_maybe, tcLookupGlobal, + + -- Local environment + tcExtendKindEnv, tcLookupLocalIds, tcInLocalScope, + tcExtendTyVarEnv, tcExtendTyVarEnvForMeths, + tcExtendLocalValEnv, tcLookup, tcLookup_maybe, tcLookupId, + + -- Global type variables tcGetGlobalTyVars, tcExtendGlobalTyVars, - InstEnv, emptyInstEnv, addToInstEnv, - lookupInstEnv, InstLookupResult(..), - tcGetInstEnv, tcSetInstEnv, classInstEnv, + -- Random useful things + RecTcEnv, tcLookupRecId, tcLookupRecId_maybe, + + -- New Ids + newLocalName, newDFunName, - badCon, badPrimOp + -- Misc + isLocalThing, tcSetEnv ) where #include "HsVersions.h" -import Id ( mkUserLocal, isDataConWrapId_maybe ) -import MkId ( mkSpecPragmaId ) -import Var ( TyVar, Id, setVarName, - idType, lazySetIdInfo, idInfo, tyVarKind, UVar, - ) -import TcType ( TcType, TcTyVar, TcTyVarSet, TcThetaType, - tcInstTyVars, zonkTcTyVars, - TcKind, - ) -import VarSet -import Type ( Kind, Type, superKind, - tyVarsOfType, tyVarsOfTypes, - splitForAllTys, splitRhoTy, splitFunTys, - splitAlgTyConApp_maybe, getTyVar, getDFunTyKey - ) -import Subst ( substTy ) -import UsageSPUtils ( unannotTy ) -import DataCon ( DataCon ) -import TyCon ( TyCon, tyConKind, tyConArity, isSynTyCon ) -import Class ( Class, ClassOpItem, ClassContext, classTyCon ) - +import RnHsSyn ( RenamedMonoBinds, RenamedSig ) import TcMonad - -import IdInfo ( vanillaIdInfo ) -import Name ( Name, OccName, Provenance(..), ExportFlag(..), NamedThing(..), - nameOccName, nameModule, getSrcLoc, mkGlobalName, - maybeWiredInTyConName, maybeWiredInIdName, isLocallyDefined, - NameEnv, emptyNameEnv, lookupNameEnv, nameEnvElts, - extendNameEnv, extendNameEnvList +import TcMType ( zonkTcTyVarsAndFV ) +import TcType ( Type, ThetaType, TcKind, TcTyVar, TcTyVarSet, + tyVarsOfTypes, tcSplitDFunTy, + getDFunTyKey, tcTyConAppTyCon + ) +import Id ( isDataConWrapId_maybe ) +import Var ( TyVar, Id, idType ) +import VarSet +import DataCon ( DataCon ) +import TyCon ( TyCon ) +import Class ( Class, ClassOpItem ) +import Name ( Name, NamedThing(..), + getSrcLoc, mkLocalName, isLocalName, nameIsLocalOrFrom + ) +import NameEnv ( NameEnv, lookupNameEnv, nameEnvElts, elemNameEnv, + extendNameEnvList, emptyNameEnv, plusNameEnv ) +import OccName ( mkDFunOcc, occNameString ) +import HscTypes ( DFunId, + PackageTypeEnv, TypeEnv, + extendTypeEnvList, extendTypeEnvWithIds, + typeEnvTyCons, typeEnvClasses, typeEnvIds, + HomeSymbolTable ) -import OccName ( mkDFunOcc, mkDefaultMethodOcc, occNameString ) import Module ( Module ) -import Unify ( unifyTyListsX, matchTys ) -import Unique ( pprUnique10, Unique, Uniquable(..) ) -import UniqFM -import Unique ( Uniquable(..) ) -import Util ( zipEqual, zipWith3Equal, mapAccumL ) -import VarEnv ( TyVarSubstEnv ) +import InstEnv ( InstEnv, emptyInstEnv ) +import HscTypes ( lookupType, TyThing(..) ) +import Util ( zipEqual ) import SrcLoc ( SrcLoc ) -import FastString ( FastString ) -import Maybes import Outputable + +import IOExts ( newIORef ) \end{code} %************************************************************************ %* * -\subsection{TcId} +\subsection{TcEnv} %* * %************************************************************************ - \begin{code} type TcId = Id -- Type may be a TcType type TcIdSet = IdSet -tcLookupDataCon :: Name -> TcM s (DataCon, [TcType], TcType) -tcLookupDataCon con_name - = tcLookupValue con_name `thenNF_Tc` \ con_id -> - case isDataConWrapId_maybe con_id of { - Nothing -> failWithTc (badCon con_id); - Just data_con -> - - tcInstId con_id `thenNF_Tc` \ (_, _, con_tau) -> - -- Ignore the con_theta; overloaded constructors only - -- behave differently when called, not when used for - -- matching. - let - (arg_tys, result_ty) = splitFunTys con_tau - in - ASSERT( maybeToBool (splitAlgTyConApp_maybe result_ty) ) - returnTc (data_con, arg_tys, result_ty) } - --- A useful function that takes an occurrence of a global thing --- and instantiates its type with fresh type variables -tcInstId :: Id - -> NF_TcM s ([TcTyVar], -- It's instantiated type - TcThetaType, -- - TcType) -- -tcInstId id - = let - (tyvars, rho) = splitForAllTys (unannotTy (idType id)) - in - tcInstTyVars tyvars `thenNF_Tc` \ (tyvars', arg_tys, tenv) -> - let - rho' = substTy tenv rho - (theta', tau') = splitRhoTy rho' - in - returnNF_Tc (tyvars', theta', tau') -\end{code} - -Between the renamer and the first invocation of the UsageSP inference, -identifiers read from interface files will have usage information in -their types, whereas other identifiers will not. The unannotTy here -in @tcInstId@ prevents this information from pointlessly propagating -further prior to the first usage inference. - - -%************************************************************************ -%* * -\subsection{TcEnv} -%* * -%************************************************************************ - -Data type declarations -~~~~~~~~~~~~~~~~~~~~~ - -\begin{code} data TcEnv = TcEnv { - tcGST :: GlobalSymbolTable, -- The symbol table at the moment we began this compilation + tcGST :: Name -> Maybe TyThing, -- The type environment at the moment we began this compilation + + tcInsts :: InstEnv, -- All instances (both imported and in this module) - tcGEnv :: NameEnv TyThing -- The global type environment we've accumulated while - -- compiling this module: + tcGEnv :: TypeEnv, -- The global type environment we've accumulated while + {- NameEnv TyThing-} -- compiling this module: -- types and classes (both imported and local) -- imported Ids - -- (Ids defined in this module are in the local envt) - -- When type checking is over we'll augment the - -- global symbol table with everything in tcGEnv - - tcInst :: InstEnv, -- All instances (both imported and in this module) + -- (Ids defined in this module start in the local envt, + -- though they move to the global envt during zonking) tcLEnv :: NameEnv TcTyThing, -- The local type environment: Ids and TyVars -- defined in this module - tcTyVars :: FreeTyVars -- Type variables free in tcLST + tcTyVars :: TcRef TcTyVarSet -- The "global tyvars" + -- Namely, the in-scope TyVars bound in tcLEnv, plus the tyvars + -- mentioned in the types of Ids bound in tcLEnv + -- Why mutable? see notes with tcGetGlobalTyVars } +\end{code} + +The Global-Env/Local-Env story +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +During type checking, we keep in the GlobalEnv + * All types and classes + * All Ids derived from types and classes (constructors, selectors) + * Imported Ids + +At the end of type checking, we zonk the local bindings, +and as we do so we add to the GlobalEnv + * Locally defined top-level Ids + +Why? Because they are now Ids not TcIds. This final GlobalEnv is +used thus: + a) fed back (via the knot) to typechecking the + unfoldings of interface signatures + + b) used to augment the GlobalSymbolTable + -type InScopeTyVars = (TcTyVarSet, -- The in-scope TyVars - TcRef TcTyVarSet) -- Free type variables of the value env - -- ...why mutable? see notes with tcGetGlobalTyVars +\begin{code} +initTcEnv :: HomeSymbolTable -> PackageTypeEnv -> IO TcEnv +initTcEnv hst pte + = do { gtv_var <- newIORef emptyVarSet ; + return (TcEnv { tcGST = lookup, + tcGEnv = emptyNameEnv, + tcInsts = emptyInstEnv, + tcLEnv = emptyNameEnv, + tcTyVars = gtv_var + })} + where + lookup name | isLocalName name = Nothing + | otherwise = lookupType hst pte name + + +tcEnvClasses env = typeEnvClasses (tcGEnv env) +tcEnvTyCons env = typeEnvTyCons (tcGEnv env) +tcEnvIds env = typeEnvIds (tcGEnv env) +tcLEnvElts env = nameEnvElts (tcLEnv env) -valueEnvIds :: ValueEnv -> [Id] -valueEnvIds ve = nameEnvElts ve +getTcGEnv (TcEnv { tcGEnv = genv }) = genv -data TcTyThing = ATyVar TyVar - | ATcId TcId - | AThing TcKind -- Used temporarily, during kind checking --- For example, when checking (forall a. T a Int): +tcInLocalScope :: TcEnv -> Name -> Bool +tcInLocalScope env v = v `elemNameEnv` (tcLEnv env) +\end{code} + +\begin{code} +data TcTyThing + = AGlobal TyThing -- Used only in the return type of a lookup + | ATcId TcId -- Ids defined in this module + | ATyVar TyVar -- Type variables + | AThing TcKind -- Used temporarily, during kind checking +-- Here's an example of how the AThing guy is used +-- Suppose we are checking (forall a. T a Int): -- 1. We first bind (a -> AThink kv), where kv is a kind variable. -- 2. Then we kind-check the (T a Int) part. -- 3. Then we zonk the kind variable. -- 4. Now we know the kind for 'a', and we add (a -> ATyVar a::K) to the environment -tyThingKind :: TyThing -> TcKind -tyThingKind (ATyVar tv) = tyVarKind tv -tyThingKind (ATyCon tc) = tyConKind tc -tyThingKind (AClass cl) = tyConKind (classTyCon cl) -- For some odd reason, - -- a class doesn't include its kind -tyThingKind (AThing k) = k +\end{code} + +This data type is used to help tie the knot + when type checking type and class declarations +\begin{code} data TyThingDetails = SynTyDetails Type - | DataTyDetails ClassContext [DataCon] [Class] - | ClassDetails ClassContext [Id] [ClassOpItem] DataCon + | DataTyDetails ThetaType [DataCon] [Id] + | ClassDetails ThetaType [Id] [ClassOpItem] DataCon + | ForeignTyDetails -- Nothing yet +\end{code} + +%************************************************************************ +%* * +\subsection{Basic lookups} +%* * +%************************************************************************ + +\begin{code} +lookup_global :: TcEnv -> Name -> Maybe TyThing + -- Try the global envt and then the global symbol table +lookup_global env name + = case lookupNameEnv (tcGEnv env) name of + Just thing -> Just thing + Nothing -> tcGST env name + +lookup_local :: TcEnv -> Name -> Maybe TcTyThing + -- Try the local envt and then try the global +lookup_local env name + = case lookupNameEnv (tcLEnv env) name of + Just thing -> Just thing + Nothing -> case lookup_global env name of + Just thing -> Just (AGlobal thing) + Nothing -> Nothing +\end{code} + +\begin{code} +type RecTcEnv = TcEnv +-- This environment is used for getting the 'right' IdInfo +-- on imported things and for looking up Ids in unfoldings +-- The environment doesn't have any local Ids in it + +tcLookupRecId_maybe :: RecTcEnv -> Name -> Maybe Id +tcLookupRecId_maybe env name = case lookup_global env name of + Just (AnId id) -> Just id + other -> Nothing + +tcLookupRecId :: RecTcEnv -> Name -> Id +tcLookupRecId env name = case lookup_global env name of + Just (AnId id) -> id + Nothing -> pprPanic "tcLookupRecId" (ppr name) +\end{code} + +%************************************************************************ +%* * +\subsection{Making new Ids} +%* * +%************************************************************************ + +Constructing new Ids + +\begin{code} +newLocalName :: Name -> NF_TcM Name +newLocalName name -- Make a clone + = tcGetUnique `thenNF_Tc` \ uniq -> + returnNF_Tc (mkLocalName uniq (getOccName name) (getSrcLoc name)) +\end{code} + +Make a name for the dict fun for an instance decl. +It's a *local* name for the moment. The CoreTidy pass +will globalise it. + +\begin{code} +newDFunName :: Class -> [Type] -> SrcLoc -> NF_TcM Name +newDFunName clas (ty:_) loc + = tcGetUnique `thenNF_Tc` \ uniq -> + returnNF_Tc (mkLocalName uniq (mkDFunOcc dfun_string) loc) + where + -- Any string that is somewhat unique will do + dfun_string = occNameString (getOccName clas) ++ occNameString (getDFunTyKey ty) -initEnv :: TcRef TcTyVarSet -> TcEnv -initEnv mut = TcEnv emptyNameEnv emptyNameEnv emptyNameEnv emptyInstEnv (emptyVarSet, mut) +newDFunName clas [] loc = pprPanic "newDFunName" (ppr clas <+> ppr loc) +\end{code} -getEnvClasses (TcEnv _ te _ _ _) = [cl | AClass cl <- nameEnvElts te] -getEnvTyCons (TcEnv _ te _ _ _) = [tc | ATyCon tc <- nameEnvElts te] +\begin{code} +isLocalThing :: NamedThing a => Module -> a -> Bool +isLocalThing mod thing = nameIsLocalOrFrom mod (getName thing) \end{code} %************************************************************************ %* * -\subsection{The usage environment} +\subsection{The global environment} %* * %************************************************************************ -Extending the usage environment +\begin{code} +tcExtendGlobalEnv :: [TyThing] -> TcM r -> TcM r +tcExtendGlobalEnv things thing_inside + = tcGetEnv `thenNF_Tc` \ env -> + let + ge' = extendTypeEnvList (tcGEnv env) things + in + tcSetEnv (env {tcGEnv = ge'}) thing_inside + + +tcExtendGlobalTypeEnv :: TypeEnv -> TcM r -> TcM r +tcExtendGlobalTypeEnv extra_env thing_inside + = tcGetEnv `thenNF_Tc` \ env -> + let + ge' = tcGEnv env `plusNameEnv` extra_env + in + tcSetEnv (env {tcGEnv = ge'}) thing_inside + +tcExtendGlobalValEnv :: [Id] -> TcM a -> TcM a +tcExtendGlobalValEnv ids thing_inside + = tcGetEnv `thenNF_Tc` \ env -> + let + ge' = extendTypeEnvWithIds (tcGEnv env) ids + in + tcSetEnv (env {tcGEnv = ge'}) thing_inside +\end{code} + \begin{code} -tcExtendUVarEnv :: Name -> UVar -> TcM s r -> TcM s r -tcExtendUVarEnv uv_name uv scope - = tcGetEnv `thenNF_Tc` \ (TcEnv ue te ve ie gtvs) -> - tcSetEnv (TcEnv (extendNameEnv ue uv_name uv) te ve ie gtvs) scope +tcLookupGlobal_maybe :: Name -> NF_TcM (Maybe TyThing) +tcLookupGlobal_maybe name + = tcGetEnv `thenNF_Tc` \ env -> + returnNF_Tc (lookup_global env name) \end{code} -Looking up in the environments. +A variety of global lookups, when we know what we are looking for. \begin{code} -tcLookupUVar :: Name -> NF_TcM s UVar -tcLookupUVar uv_name - = tcGetEnv `thenNF_Tc` \ (TcEnv ue te ve _ gtvs) -> - case lookupNameEnv ue uv_name of - Just uv -> returnNF_Tc uv - Nothing -> failWithTc (uvNameOutOfScope uv_name) -\end{code} +tcLookupGlobal :: Name -> NF_TcM TyThing +tcLookupGlobal name + = tcLookupGlobal_maybe name `thenNF_Tc` \ maybe_thing -> + case maybe_thing of + Just thing -> returnNF_Tc thing + other -> notFound "tcLookupGlobal" name + +tcLookupGlobalId :: Name -> NF_TcM Id +tcLookupGlobalId name + = tcLookupGlobal_maybe name `thenNF_Tc` \ maybe_id -> + case maybe_id of + Just (AnId id) -> returnNF_Tc id + other -> notFound "tcLookupGlobalId" name + +tcLookupDataCon :: Name -> TcM DataCon +tcLookupDataCon con_name + = tcLookupGlobalId con_name `thenNF_Tc` \ con_id -> + case isDataConWrapId_maybe con_id of + Just data_con -> returnTc data_con + Nothing -> failWithTc (badCon con_id) + + +tcLookupClass :: Name -> NF_TcM Class +tcLookupClass name + = tcLookupGlobal_maybe name `thenNF_Tc` \ maybe_clas -> + case maybe_clas of + Just (AClass clas) -> returnNF_Tc clas + other -> notFound "tcLookupClass" name + +tcLookupTyCon :: Name -> NF_TcM TyCon +tcLookupTyCon name + = tcLookupGlobal_maybe name `thenNF_Tc` \ maybe_tc -> + case maybe_tc of + Just (ATyCon tc) -> returnNF_Tc tc + other -> notFound "tcLookupTyCon" name + +tcLookupId :: Name -> NF_TcM Id +tcLookupId name + = tcLookup name `thenNF_Tc` \ thing -> + case thing of + ATcId tc_id -> returnNF_Tc tc_id + AGlobal (AnId id) -> returnNF_Tc id + other -> pprPanic "tcLookupId" (ppr name) + +tcLookupLocalIds :: [Name] -> NF_TcM [TcId] +tcLookupLocalIds ns + = tcGetEnv `thenNF_Tc` \ env -> + returnNF_Tc (map (lookup (tcLEnv env)) ns) + where + lookup lenv name = case lookupNameEnv lenv name of + Just (ATcId id) -> id + other -> pprPanic "tcLookupLocalIds" (ppr name) +\end{code} %************************************************************************ %* * -\subsection{The type environment} +\subsection{The local environment} %* * %************************************************************************ \begin{code} -tcExtendKindEnv :: [(Name,TcKind)] -> TcM s r -> TcM s r -tcExtendKindEnv pairs scope - = tcGetEnv `thenNF_Tc` \ (TcEnv ue te ve ie gtvs) -> +tcLookup_maybe :: Name -> NF_TcM (Maybe TcTyThing) +tcLookup_maybe name + = tcGetEnv `thenNF_Tc` \ env -> + returnNF_Tc (lookup_local env name) + +tcLookup :: Name -> NF_TcM TcTyThing +tcLookup name + = tcLookup_maybe name `thenNF_Tc` \ maybe_thing -> + case maybe_thing of + Just thing -> returnNF_Tc thing + other -> notFound "tcLookup" name + -- Extract the IdInfo from an IfaceSig imported from an interface file +\end{code} + + +\begin{code} +tcExtendKindEnv :: [(Name,TcKind)] -> TcM r -> TcM r +tcExtendKindEnv pairs thing_inside + = tcGetEnv `thenNF_Tc` \ env -> let - te' = extendNameEnvList te [(n, AThing k) | (n,k) <- pairs] + le' = extendNameEnvList (tcLEnv env) [(n, AThing k) | (n,k) <- pairs] -- No need to extend global tyvars for kind checking in - tcSetEnv (TcEnv ue te' ve ie gtvs) scope + tcSetEnv (env {tcLEnv = le'}) thing_inside -tcExtendTyVarEnv :: [TyVar] -> TcM s r -> TcM s r -tcExtendTyVarEnv tyvars scope - = tcGetEnv `thenNF_Tc` \ (TcEnv ue te ve ie (in_scope_tvs, gtvs)) -> +tcExtendTyVarEnv :: [TyVar] -> TcM r -> TcM r +tcExtendTyVarEnv tyvars thing_inside + = tcGetEnv `thenNF_Tc` \ env@(TcEnv {tcLEnv = le, tcTyVars = gtvs}) -> let - te' = extendNameEnvList te [ (getName tv, ATyVar tv) | tv <- tyvars] - new_tv_set = mkVarSet tyvars - in_scope_tvs' = in_scope_tvs `unionVarSet` new_tv_set + le' = extendNameEnvList le [ (getName tv, ATyVar tv) | tv <- tyvars] + new_tv_set = mkVarSet tyvars in -- It's important to add the in-scope tyvars to the global tyvar set -- as well. Consider @@ -258,7 +399,7 @@ tcExtendTyVarEnv tyvars scope -- class and instance decls, when we mustn't generalise the class tyvars -- when typechecking the methods. tc_extend_gtvs gtvs new_tv_set `thenNF_Tc` \ gtvs' -> - tcSetEnv (TcEnv ue te' ve ie (in_scope_tvs', gtvs')) scope + tcSetEnv (env {tcLEnv = le', tcTyVars = gtvs'}) thing_inside -- This variant, tcExtendTyVarEnvForMeths, takes *two* bunches of tyvars: -- the signature tyvars contain the original names @@ -266,222 +407,62 @@ tcExtendTyVarEnv tyvars scope -- It's needed when typechecking the method bindings of class and instance decls -- It does *not* extend the global tyvars; tcMethodBind does that for itself -tcExtendTyVarEnvForMeths :: [TyVar] -> [TcTyVar] -> TcM s r -> TcM s r +tcExtendTyVarEnvForMeths :: [TyVar] -> [TcTyVar] -> TcM r -> TcM r tcExtendTyVarEnvForMeths sig_tyvars inst_tyvars thing_inside - = tcGetEnv `thenNF_Tc` \ (TcEnv ue te ve ie gtvs) -> + = tcGetEnv `thenNF_Tc` \ env -> let - te' = extendNameEnvList te stuff + le' = extendNameEnvList (tcLEnv env) stuff + stuff = [ (getName sig_tv, ATyVar inst_tv) + | (sig_tv, inst_tv) <- zipEqual "tcMeth" sig_tyvars inst_tyvars + ] in - tcSetEnv (TcEnv ue te' ve ie gtvs) thing_inside - where - stuff = [ (getName sig_tv, ATyVar inst_tv) - | (sig_tv, inst_tv) <- zipEqual "tcMeth" sig_tyvars inst_tyvars - ] - -tcExtendGlobalTyVars extra_global_tvs scope - = tcGetEnv `thenNF_Tc` \ (TcEnv ue te ve ie (in_scope,gtvs)) -> - tc_extend_gtvs gtvs extra_global_tvs `thenNF_Tc` \ gtvs' -> - tcSetEnv (TcEnv ue te ve ie (in_scope,gtvs')) scope - -tc_extend_gtvs gtvs extra_global_tvs - = tcReadMutVar gtvs `thenNF_Tc` \ global_tvs -> - let - new_global_tyvars = global_tvs `unionVarSet` extra_global_tvs - in - tcNewMutVar new_global_tyvars -\end{code} - -@tcGetGlobalTyVars@ returns a fully-zonked set of tyvars free in the environment. -To improve subsequent calls to the same function it writes the zonked set back into -the environment. - -\begin{code} -tcGetGlobalTyVars :: NF_TcM s TcTyVarSet -tcGetGlobalTyVars - = tcGetEnv `thenNF_Tc` \ (TcEnv ue te ve ie (_,gtvs)) -> - tcReadMutVar gtvs `thenNF_Tc` \ global_tvs -> - zonkTcTyVars (varSetElems global_tvs) `thenNF_Tc` \ global_tys' -> - let - global_tvs' = (tyVarsOfTypes global_tys') - in - tcWriteMutVar gtvs global_tvs' `thenNF_Tc_` - returnNF_Tc global_tvs' - -tcGetInScopeTyVars :: NF_TcM s [TcTyVar] -tcGetInScopeTyVars - = tcGetEnv `thenNF_Tc` \ (TcEnv ue te ve ie (in_scope_tvs, gtvs)) -> - returnNF_Tc (varSetElems in_scope_tvs) + tcSetEnv (env {tcLEnv = le'}) thing_inside \end{code} -Type constructors and classes - \begin{code} -tcExtendTypeEnv :: [(Name, TyThing)] -> TcM s r -> TcM s r -tcExtendTypeEnv bindings scope - = ASSERT( null [tv | (_, ATyVar tv) <- bindings] ) - -- Not for tyvars; use tcExtendTyVarEnv - tcGetEnv `thenNF_Tc` \ (TcEnv ue te ve ie gtvs) -> +tcExtendLocalValEnv :: [(Name,TcId)] -> TcM a -> TcM a +tcExtendLocalValEnv names_w_ids thing_inside + = tcGetEnv `thenNF_Tc` \ env -> let - te' = extendNameEnvList te bindings + extra_global_tyvars = tyVarsOfTypes [idType id | (name,id) <- names_w_ids] + extra_env = [(name, ATcId id) | (name,id) <- names_w_ids] + le' = extendNameEnvList (tcLEnv env) extra_env in - tcSetEnv (TcEnv ue te' ve ie gtvs) scope -\end{code} - - -Looking up in the environments. - -\begin{code} -tcLookupTy :: Name -> NF_TcM s TyThing -tcLookupTy name - = tcGetEnv `thenNF_Tc` \ (TcEnv ue te ve ie gtvs) -> - case lookupNameEnv te name of { - Just thing -> returnNF_Tc thing ; - Nothing -> - - case maybeWiredInTyConName name of - Just tc -> returnNF_Tc (ATyCon tc) - - Nothing -> -- This can happen if an interface-file - -- unfolding is screwed up - failWithTc (tyNameOutOfScope name) - } - -tcLookupClassByKey :: Unique -> NF_TcM s Class -tcLookupClassByKey key - = tcGetEnv `thenNF_Tc` \ (TcEnv ue te ve ie gtvs) -> - case lookupUFM_Directly te key of - Just (AClass cl) -> returnNF_Tc cl - other -> pprPanic "tcLookupClassByKey:" (pprUnique10 key) - -tcLookupClassByKey_maybe :: Unique -> NF_TcM s (Maybe Class) -tcLookupClassByKey_maybe key - = tcGetEnv `thenNF_Tc` \ (TcEnv ue te ve ie gtvs) -> - case lookupUFM_Directly te key of - Just (AClass cl) -> returnNF_Tc (Just cl) - other -> returnNF_Tc Nothing - -tcLookupTyConByKey :: Unique -> NF_TcM s TyCon -tcLookupTyConByKey key - = tcGetEnv `thenNF_Tc` \ (TcEnv ue te ve ie gtvs) -> - case lookupUFM_Directly te key of - Just (ATyCon tc) -> returnNF_Tc tc - other -> pprPanic "tcLookupTyConByKey:" (pprUnique10 key) + tc_extend_gtvs (tcTyVars env) extra_global_tyvars `thenNF_Tc` \ gtvs' -> + tcSetEnv (env {tcLEnv = le', tcTyVars = gtvs'}) thing_inside \end{code} - - %************************************************************************ %* * -\subsection{The value environment} +\subsection{The global tyvars} %* * %************************************************************************ \begin{code} -tcExtendGlobalValEnv :: [Id] -> TcM s a -> TcM s a -tcExtendGlobalValEnv ids scope - = tcGetEnv `thenNF_Tc` \ (TcEnv ue te ve ie gtvs) -> - let - ve' = addListToUFM_Directly ve [(getUnique id, id) | id <- ids] - in - tcSetEnv (TcEnv ue te ve' ie gtvs) scope - -tcExtendLocalValEnv :: [(Name,TcId)] -> TcM s a -> TcM s a -tcExtendLocalValEnv names_w_ids scope - = tcGetEnv `thenNF_Tc` \ (TcEnv ue te ve ie (in_scope_tvs,gtvs)) -> - tcReadMutVar gtvs `thenNF_Tc` \ global_tvs -> - let - ve' = extendNameEnvList ve names_w_ids - extra_global_tyvars = tyVarsOfTypes (map (idType . snd) names_w_ids) - in - tc_extend_gtvs gtvs extra_global_tyvars `thenNF_Tc` \ gtvs' -> - tcSetEnv (TcEnv ue te ve' ie (in_scope_tvs,gtvs')) scope -\end{code} - - -\begin{code} -tcLookupValue :: Name -> NF_TcM s Id -- Panics if not found -tcLookupValue name - = case maybeWiredInIdName name of - Just id -> returnNF_Tc id - Nothing -> tcGetEnv `thenNF_Tc` \ (TcEnv ue te ve ie gtvs) -> - returnNF_Tc (lookupWithDefaultUFM ve def name) - where - wired_in = case maybeWiredInIdName name of - Just id -> True - Nothing -> False - def = pprPanic "tcLookupValue:" (ppr name <+> ppr wired_in) - -tcLookupValueMaybe :: Name -> NF_TcM s (Maybe Id) -tcLookupValueMaybe name - = case maybeWiredInIdName name of - Just id -> returnNF_Tc (Just id) - Nothing -> tcGetEnv `thenNF_Tc` \ (TcEnv ue te ve ie gtvs) -> - returnNF_Tc (lookupNameEnv ve name) - -tcLookupValueByKey :: Unique -> NF_TcM s Id -- Panics if not found -tcLookupValueByKey key - = tcGetEnv `thenNF_Tc` \ (TcEnv ue te ve ie gtvs) -> - returnNF_Tc (explicitLookupValueByKey ve key) - -tcLookupValueByKeyMaybe :: Unique -> NF_TcM s (Maybe Id) -tcLookupValueByKeyMaybe key - = tcGetEnv `thenNF_Tc` \ (TcEnv ue te ve ie gtvs) -> - returnNF_Tc (lookupUFM_Directly ve key) - -tcGetValueEnv :: NF_TcM s ValueEnv -tcGetValueEnv - = tcGetEnv `thenNF_Tc` \ (TcEnv ue te ve ie gtvs) -> - returnNF_Tc ve - - -tcSetValueEnv :: ValueEnv -> TcM s a -> TcM s a -tcSetValueEnv ve scope - = tcGetEnv `thenNF_Tc` \ (TcEnv ue te _ ie gtvs) -> - tcSetEnv (TcEnv ue te ve ie gtvs) scope - --- Non-monadic version, environment given explicitly -explicitLookupValueByKey :: ValueEnv -> Unique -> Id -explicitLookupValueByKey ve key - = lookupWithDefaultUFM_Directly ve def key - where - def = pprPanic "lookupValueByKey:" (pprUnique10 key) - -explicitLookupValue :: ValueEnv -> Name -> Maybe Id -explicitLookupValue ve name - = case maybeWiredInIdName name of - Just id -> Just id - Nothing -> lookupNameEnv ve name +tcExtendGlobalTyVars extra_global_tvs thing_inside + = tcGetEnv `thenNF_Tc` \ env -> + tc_extend_gtvs (tcTyVars env) extra_global_tvs `thenNF_Tc` \ gtvs' -> + tcSetEnv (env {tcTyVars = gtvs'}) thing_inside - -- Extract the IdInfo from an IfaceSig imported from an interface file -tcAddImportedIdInfo :: ValueEnv -> Id -> Id -tcAddImportedIdInfo unf_env id - | isLocallyDefined id -- Don't look up locally defined Ids, because they - -- have explicit local definitions, so we get a black hole! - = id - | otherwise - = id `lazySetIdInfo` new_info - -- The Id must be returned without a data dependency on maybe_id - where - new_info = case explicitLookupValue unf_env (getName id) of - Nothing -> vanillaIdInfo - Just imported_id -> idInfo imported_id - -- ToDo: could check that types are the same +tc_extend_gtvs gtvs extra_global_tvs + = tcReadMutVar gtvs `thenNF_Tc` \ global_tvs -> + tcNewMutVar (global_tvs `unionVarSet` extra_global_tvs) \end{code} -Constructing new Ids +@tcGetGlobalTyVars@ returns a fully-zonked set of tyvars free in the environment. +To improve subsequent calls to the same function it writes the zonked set back into +the environment. \begin{code} -newLocalId :: OccName -> TcType -> SrcLoc -> NF_TcM s TcId -newLocalId name ty loc - = tcGetUnique `thenNF_Tc` \ uniq -> - returnNF_Tc (mkUserLocal name uniq ty loc) - -newSpecPragmaId :: Name -> TcType -> NF_TcM s TcId -newSpecPragmaId name ty - = tcGetUnique `thenNF_Tc` \ uniq -> - returnNF_Tc (mkSpecPragmaId (nameOccName name) uniq ty (getSrcLoc name)) +tcGetGlobalTyVars :: NF_TcM TcTyVarSet +tcGetGlobalTyVars + = tcGetEnv `thenNF_Tc` \ (TcEnv {tcTyVars = gtv_var}) -> + tcReadMutVar gtv_var `thenNF_Tc` \ gbl_tvs -> + zonkTcTyVarsAndFV (varSetElems gbl_tvs) `thenNF_Tc` \ gbl_tvs' -> + tcWriteMutVar gtv_var gbl_tvs' `thenNF_Tc_` + returnNF_Tc gbl_tvs' \end{code} @@ -492,285 +473,57 @@ newSpecPragmaId name ty %************************************************************************ \begin{code} -tcGetInstEnv :: NF_TcM s InstEnv -tcGetInstEnv = tcGetEnv `thenNF_Tc` \ (TcEnv ue te ve ie (_,gtvs)) -> - returnNF_Tc ie - -tcSetInstEnv :: InstEnv -> TcM s a -> TcM s a -tcSetInstEnv ie scope - = tcGetEnv `thenNF_Tc` \ (TcEnv ue te ve _ gtvs) -> - tcSetEnv (TcEnv ue te ve ie gtvs) scope +tcGetInstEnv :: NF_TcM InstEnv +tcGetInstEnv = tcGetEnv `thenNF_Tc` \ env -> + returnNF_Tc (tcInsts env) + +tcSetInstEnv :: InstEnv -> TcM a -> TcM a +tcSetInstEnv ie thing_inside + = tcGetEnv `thenNF_Tc` \ env -> + tcSetEnv (env {tcInsts = ie}) thing_inside \end{code} -\begin{code} -type InstEnv = UniqFM ClsInstEnv -- Maps Class to instances for that class -type ClsInstEnv = [(TyVarSet, [Type], Id)] -- The instances for a particular class - -classInstEnv :: InstEnv -> Class -> ClsInstEnv -classInstEnv env cls = lookupWithDefaultUFM env [] cls -\end{code} - -A @ClsInstEnv@ lives inside a class, and identifies all the instances -of that class. The @Id@ inside a ClsInstEnv mapping is the dfun for -that instance. - -If class C maps to a list containing the item ([a,b], [t1,t2,t3], dfun), then - - forall a b, C t1 t2 t3 can be constructed by dfun - -or, to put it another way, we have - - instance (...) => C t1 t2 t3, witnessed by dfun - -There is an important consistency constraint in the elements of a ClsInstEnv: - - * [a,b] must be a superset of the free vars of [t1,t2,t3] - - * The dfun must itself be quantified over [a,b] - -Thus, the @ClassInstEnv@ for @Eq@ might contain the following entry: - [a] ===> dfun_Eq_List :: forall a. Eq a => Eq [a] -The "a" in the pattern must be one of the forall'd variables in -the dfun type. - - - -Notes on overlapping instances -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -In some ClsInstEnvs, overlap is prohibited; that is, no pair of templates unify. - -In others, overlap is permitted, but only in such a way that one can make -a unique choice when looking up. That is, overlap is only permitted if -one template matches the other, or vice versa. So this is ok: - - [a] [Int] - -but this is not - - (Int,a) (b,Int) - -If overlap is permitted, the list is kept most specific first, so that -the first lookup is the right choice. - - -For now we just use association lists. - -\subsection{Avoiding a problem with overlapping} - -Consider this little program: - -\begin{pseudocode} - class C a where c :: a - class C a => D a where d :: a - - instance C Int where c = 17 - instance D Int where d = 13 - - instance C a => C [a] where c = [c] - instance ({- C [a], -} D a) => D [a] where d = c - - instance C [Int] where c = [37] - - main = print (d :: [Int]) -\end{pseudocode} - -What do you think `main' prints (assuming we have overlapping instances, and -all that turned on)? Well, the instance for `D' at type `[a]' is defined to -be `c' at the same type, and we've got an instance of `C' at `[Int]', so the -answer is `[37]', right? (the generic `C [a]' instance shouldn't apply because -the `C [Int]' instance is more specific). - -Ghc-4.04 gives `[37]', while ghc-4.06 gives `[17]', so 4.06 is wrong. That -was easy ;-) Let's just consult hugs for good measure. Wait - if I use old -hugs (pre-September99), I get `[17]', and stranger yet, if I use hugs98, it -doesn't even compile! What's going on!? - -What hugs complains about is the `D [a]' instance decl. - -\begin{pseudocode} - ERROR "mj.hs" (line 10): Cannot build superclass instance - *** Instance : D [a] - *** Context supplied : D a - *** Required superclass : C [a] -\end{pseudocode} - -You might wonder what hugs is complaining about. It's saying that you -need to add `C [a]' to the context of the `D [a]' instance (as appears -in comments). But there's that `C [a]' instance decl one line above -that says that I can reduce the need for a `C [a]' instance to the -need for a `C a' instance, and in this case, I already have the -necessary `C a' instance (since we have `D a' explicitly in the -context, and `C' is a superclass of `D'). - -Unfortunately, the above reasoning indicates a premature commitment to the -generic `C [a]' instance. I.e., it prematurely rules out the more specific -instance `C [Int]'. This is the mistake that ghc-4.06 makes. The fix is to -add the context that hugs suggests (uncomment the `C [a]'), effectively -deferring the decision about which instance to use. - -Now, interestingly enough, 4.04 has this same bug, but it's covered up -in this case by a little known `optimization' that was disabled in -4.06. Ghc-4.04 silently inserts any missing superclass context into -an instance declaration. In this case, it silently inserts the `C -[a]', and everything happens to work out. - -(See `basicTypes/MkId:mkDictFunId' for the code in question. Search for -`Mark Jones', although Mark claims no credit for the `optimization' in -question, and would rather it stopped being called the `Mark Jones -optimization' ;-) - -So, what's the fix? I think hugs has it right. Here's why. Let's try -something else out with ghc-4.04. Let's add the following line: - - d' :: D a => [a] - d' = c - -Everyone raise their hand who thinks that `d :: [Int]' should give a -different answer from `d' :: [Int]'. Well, in ghc-4.04, it does. The -`optimization' only applies to instance decls, not to regular -bindings, giving inconsistent behavior. - -Old hugs had this same bug. Here's how we fixed it: like GHC, the -list of instances for a given class is ordered, so that more specific -instances come before more generic ones. For example, the instance -list for C might contain: - ..., C Int, ..., C a, ... -When we go to look for a `C Int' instance we'll get that one first. -But what if we go looking for a `C b' (`b' is unconstrained)? We'll -pass the `C Int' instance, and keep going. But if `b' is -unconstrained, then we don't know yet if the more specific instance -will eventually apply. GHC keeps going, and matches on the generic `C -a'. The fix is to, at each step, check to see if there's a reverse -match, and if so, abort the search. This prevents hugs from -prematurely chosing a generic instance when a more specific one -exists. +%************************************************************************ +%* * +\subsection{The InstInfo type} +%* * +%************************************************************************ ---Jeff +The InstInfo type summarises the information in an instance declaration -\begin{code} -emptyInstEnv :: InstEnv -emptyInstEnv = emptyUFM -\end{code} + instance c => k (t tvs) where b -@lookupInstEnv@ looks up in a @InstEnv@, using a one-way match. Since -the env is kept ordered, the first match must be the only one. The -thing we are looking up can have an arbitrary "flexi" part. +It is used just for *local* instance decls (not ones from interface files). +But local instance decls includes + - derived ones + - generic ones +as well as explicit user written ones. \begin{code} -lookupInstEnv :: InstEnv -- The envt - -> Class -> [Type] -- Key - -> InstLookupResult - -data InstLookupResult - = FoundInst -- There is a (template,substitution) pair - -- that makes the template match the key, - -- and no template is an instance of the key - TyVarSubstEnv Id - - | NoMatch Bool -- Boolean is true iff there is at least one - -- template that matches the key. - -- (but there are other template(s) that are - -- instances of the key, so we don't report - -- FoundInst) - -- The NoMatch True case happens when we look up - -- Foo [a] - -- in an InstEnv that has entries for - -- Foo [Int] - -- Foo [b] - -- Then which we choose would depend on the way in which 'a' - -- is instantiated. So we say there is no match, but identify - -- it as ambiguous case in the hope of giving a better error msg. - -- See the notes above from Jeff Lewis - -lookupInstEnv env key_cls key_tys - = find (classInstEnv env key_cls) - where - key_vars = tyVarsOfTypes key_tys - - find [] = NoMatch False - find ((tpl_tyvars, tpl, val) : rest) - = case matchTys tpl_tyvars tpl key_tys of - Nothing -> - case matchTys key_vars key_tys tpl of - Nothing -> find rest - Just (_, _) -> NoMatch (any_match rest) - Just (subst, leftovers) -> ASSERT( null leftovers ) - FoundInst subst val - - any_match rest = or [ maybeToBool (matchTys tvs tpl key_tys) - | (tvs,tpl,_) <- rest - ] -\end{code} - -@addToClsInstEnv@ extends a @ClsInstEnv@, checking for overlaps. - -A boolean flag controls overlap reporting. +data InstInfo + = InstInfo { + iDFunId :: DFunId, -- The dfun id + iBinds :: RenamedMonoBinds, -- Bindings, b + iPrags :: [RenamedSig] -- User pragmas recorded for generating specialised instances + } -True => overlap is permitted, but only if one template matches the other; - not if they unify but neither is + | NewTypeDerived { -- Used for deriving instances of newtypes, where the + -- witness dictionary is identical to the argument dictionary + -- Hence no bindings. + iDFunId :: DFunId -- The dfun id + } -\begin{code} -addToInstEnv :: Bool -- True <=> overlap permitted - -> InstEnv -- Envt - -> Class -> [TyVar] -> [Type] -> Id -- New item - -> MaybeErr InstEnv -- Success... - ([Type], Id) -- Failure: Offending overlap - -addToInstEnv overlap_ok inst_env clas ins_tvs ins_tys value - = case insert_into (classInstEnv inst_env clas) of - Failed stuff -> Failed stuff - Succeeded new_env -> Succeeded (addToUFM inst_env clas new_env) - - where - ins_tv_set = mkVarSet ins_tvs - ins_item = (ins_tv_set, ins_tys, value) - - insert_into [] = returnMaB [ins_item] - insert_into env@(cur_item@(tpl_tvs, tpl_tys, val) : rest) - - -- FAIL if: - -- (a) they are the same, or - -- (b) they unify, and any sort of overlap is prohibited, - -- (c) they unify but neither is more specific than t'other - | identical - || (unifiable && not overlap_ok) - || (unifiable && not (ins_item_more_specific || cur_item_more_specific)) - = failMaB (tpl_tys, val) - - -- New item is an instance of current item, so drop it here - | ins_item_more_specific = returnMaB (ins_item : env) - - -- Otherwise carry on - | otherwise = insert_into rest `thenMaB` \ rest' -> - returnMaB (cur_item : rest') - where - unifiable = maybeToBool (unifyTyListsX (ins_tv_set `unionVarSet` tpl_tvs) tpl_tys ins_tys) - ins_item_more_specific = maybeToBool (matchTys tpl_tvs tpl_tys ins_tys) - cur_item_more_specific = maybeToBool (matchTys ins_tv_set ins_tys tpl_tys) - identical = ins_item_more_specific && cur_item_more_specific -\end{code} +pprInstInfo info = vcat [ptext SLIT("InstInfo:") <+> ppr (idType (iDFunId info))] -Make a name for the dict fun for an instance decl +simpleInstInfoTy :: InstInfo -> Type +simpleInstInfoTy info = case tcSplitDFunTy (idType (iDFunId info)) of + (_, _, _, [ty]) -> ty -\begin{code} -newDFunName :: Module -> Class -> [Type] -> SrcLoc -> NF_TcM s Name -newDFunName mod clas (ty:_) loc - = tcGetDFunUniq dfun_string `thenNF_Tc` \ inst_uniq -> - tcGetUnique `thenNF_Tc` \ uniq -> - returnNF_Tc (mkGlobalName uniq mod - (mkDFunOcc dfun_string inst_uniq) - (LocalDef loc Exported)) - where - -- Any string that is somewhat unique will do - dfun_string = occNameString (getOccName clas) ++ occNameString (getDFunTyKey ty) - -newDefaultMethodName :: Name -> SrcLoc -> NF_TcM s Name -newDefaultMethodName op_name loc - = tcGetUnique `thenNF_Tc` \ uniq -> - returnNF_Tc (mkGlobalName uniq (nameModule op_name) - (mkDefaultMethodOcc (getOccName op_name)) - (LocalDef loc Exported)) +simpleInstInfoTyCon :: InstInfo -> TyCon + -- Gets the type constructor for a simple instance declaration, + -- i.e. one of the form instance (...) => C (T a b c) where ... +simpleInstInfoTyCon inst = tcTyConAppTyCon (simpleInstInfoTy inst) \end{code} @@ -781,14 +534,8 @@ newDefaultMethodName op_name loc %************************************************************************ \begin{code} -badCon con_id - = quotes (ppr con_id) <+> ptext SLIT("is not a data constructor") -badPrimOp op - = quotes (ppr op) <+> ptext SLIT("is not a primop") - -uvNameOutOfScope name - = ptext SLIT("UVar") <+> quotes (ppr name) <+> ptext SLIT("is not in scope") +badCon con_id = quotes (ppr con_id) <+> ptext SLIT("is not a data constructor") -tyNameOutOfScope name - = quotes (ppr name) <+> ptext SLIT("is not in scope") +notFound wheRe name = failWithTc (text wheRe <> colon <+> quotes (ppr name) <+> + ptext SLIT("is not in scope")) \end{code}