X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FInst.lhs;h=f27a78255542fb0f2b6d03b7cb0d885f2d053a5c;hb=5f553f0c0508cb09b75f78e6c2ac1baa4c01b6aa;hp=86522ad04548a307ce332a1b409de15346a64d63;hpb=8a86866e9e382c1d4d06cad722ddbe965d09997c;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/Inst.lhs b/ghc/compiler/typecheck/Inst.lhs index 86522ad..f27a782 100644 --- a/ghc/compiler/typecheck/Inst.lhs +++ b/ghc/compiler/typecheck/Inst.lhs @@ -5,28 +5,29 @@ \begin{code} module Inst ( - LIE, emptyLIE, unitLIE, plusLIE, consLIE, - plusLIEs, mkLIE, isEmptyLIE, lieToList, listToLIE, showLIE, Inst, - pprInst, pprInsts, pprInstsInFull, tidyInsts, tidyMoreInsts, + pprInst, pprInsts, pprInstsInFull, pprDFuns, + tidyInsts, tidyMoreInsts, newDictsFromOld, newDicts, cloneDict, newOverloadedLit, newIPDict, newMethod, newMethodFromName, newMethodWithGivenTy, - tcInstClassOp, tcInstCall, tcInstDataCon, tcSyntaxName, + tcInstClassOp, tcInstCall, tcInstDataCon, + tcSyntaxName, tcStdSyntaxName, tyVarsOfInst, tyVarsOfInsts, tyVarsOfLIE, ipNamesOfInst, ipNamesOfInsts, fdPredsOfInst, fdPredsOfInsts, instLoc, getDictClassTys, dictPred, lookupInst, LookupInstResult(..), + tcExtendLocalInstEnv, tcGetInstEnvs, isDict, isClassDict, isMethod, isLinearInst, linearInstType, isIPDict, isInheritableInst, isTyVarDict, isStdClassTyVarDict, isMethodFor, - instBindingRequired, instCanBeGeneralised, + instBindingRequired, zonkInst, zonkInsts, instToId, instName, @@ -36,46 +37,54 @@ module Inst ( #include "HsVersions.h" -import {-# SOURCE #-} TcExpr( tcExpr ) +import {-# SOURCE #-} TcExpr( tcCheckSigma ) +import {-# SOURCE #-} TcUnify ( unifyTauTy ) -- Used in checkKind (sigh) -import HsSyn ( HsLit(..), HsOverLit(..), HsExpr(..) ) -import TcHsSyn ( TcExpr, TcId, TcIdSet, - mkHsTyApp, mkHsDictApp, mkHsConApp, zonkId, +import HsSyn ( HsLit(..), HsOverLit(..), HsExpr(..), LHsExpr, mkHsApp ) +import TcHsSyn ( TcId, TcIdSet, + mkHsTyApp, mkHsDictApp, mkHsConApp, zonkId, mkCoercion, ExprCoFn ) import TcRnMonad -import TcEnv ( tcGetInstEnv, tcLookupId, tcLookupTyCon, checkWellStaged, topIdLvl ) -import InstEnv ( InstLookupResult(..), lookupInstEnv ) -import TcMType ( zonkTcType, zonkTcTypes, zonkTcPredType, zapToType, +import TcEnv ( tcLookupId, checkWellStaged, topIdLvl, tcMetaTy ) +import InstEnv ( DFunId, InstEnv, lookupInstEnv, checkFunDeps, extendInstEnv ) +import TcIface ( loadImportedInsts ) +import TcMType ( zonkTcType, zonkTcTypes, zonkTcPredType, zonkTcThetaType, tcInstTyVar, tcInstType, tcInstTyVars ) import TcType ( Type, TcType, TcThetaType, TcTyVarSet, - SourceType(..), PredType, TyVarDetails(VanillaTv), + PredType(..), TyVarDetails(VanillaTv), typeKind, tcSplitForAllTys, tcSplitForAllTys, mkTyConApp, - tcSplitPhiTy, mkGenTyConApp, + tcSplitPhiTy, tcIsTyVarTy, tcSplitDFunTy, isIntTy,isFloatTy, isIntegerTy, isDoubleTy, tcIsTyVarTy, mkPredTy, mkTyVarTy, mkTyVarTys, tyVarsOfType, tyVarsOfTypes, tyVarsOfPred, tidyPred, - isClassPred, isTyVarClassPred, isLinearPred, predHasFDs, + isClassPred, isTyVarClassPred, isLinearPred, getClassPredTys, getClassPredTys_maybe, mkPredName, - isInheritablePred, isIPPred, - tidyType, tidyTypes, tidyFreeTyVars, tcSplitSigmaTy + isInheritablePred, isIPPred, matchTys, + tidyType, tidyTypes, tidyFreeTyVars, tcSplitSigmaTy, + pprPred, pprParendType, pprThetaArrow, pprClassPred ) +import Kind ( isSubKind ) +import HscTypes ( ExternalPackageState(..) ) import CoreFVs ( idFreeTyVars ) import DataCon ( DataCon,dataConSig ) import Id ( Id, idName, idType, mkUserLocal, mkSysLocal, mkLocalId, setIdUnique ) -import PrelInfo ( isStandardClass, isCcallishClass, isNoDictClass ) -import Name ( Name, mkMethodOcc, getOccName ) -import PprType ( pprPred, pprParendType ) +import PrelInfo ( isStandardClass, isNoDictClass ) +import Name ( Name, mkMethodOcc, getOccName, getSrcLoc, isHomePackageName, isInternalName ) +import NameSet ( addOneToNameSet ) import Subst ( substTy, substTyWith, substTheta, mkTyVarSubst ) import Literal ( inIntRange ) -import Var ( TyVar ) +import Var ( TyVar, tyVarKind ) import VarEnv ( TidyEnv, emptyTidyEnv, lookupSubstEnv, SubstResult(..) ) -import VarSet ( elemVarSet, emptyVarSet, unionVarSet ) +import VarSet ( elemVarSet, emptyVarSet, unionVarSet, mkVarSet ) import TysWiredIn ( floatDataCon, doubleDataCon ) -import PrelNames( fromIntegerName, fromRationalName, rationalTyConName ) +import PrelNames ( integerTyConName, fromIntegerName, fromRationalName, rationalTyConName ) import BasicTypes( IPName(..), mapIPName, ipNameName ) import UniqSupply( uniqsFromSupply ) +import SrcLoc ( mkSrcSpan, noLoc, Located(..) ) +import CmdLineOpts( DynFlags, DynFlag( Opt_AllowUndecidableInstances ), dopt ) +import Maybes ( isJust ) import Outputable \end{code} @@ -101,11 +110,14 @@ dictPred inst = pprPanic "dictPred" (ppr inst) getDictClassTys (Dict _ pred _) = getClassPredTys pred -- fdPredsOfInst is used to get predicates that contain functional --- dependencies; i.e. should participate in improvement -fdPredsOfInst (Dict _ pred _) | predHasFDs pred = [pred] - | otherwise = [] -fdPredsOfInst (Method _ _ _ theta _ _) = filter predHasFDs theta -fdPredsOfInst other = [] +-- dependencies *or* might do so. The "might do" part is because +-- a constraint (C a b) might have a superclass with FDs +-- Leaving these in is really important for the call to fdPredsOfInsts +-- in TcSimplify.inferLoop, because the result is fed to 'grow', +-- which is supposed to be conservative +fdPredsOfInst (Dict _ pred _) = [pred] +fdPredsOfInst (Method _ _ _ theta _ _) = theta +fdPredsOfInst other = [] -- LitInsts etc fdPredsOfInsts :: [Inst] -> [PredType] fdPredsOfInsts insts = concatMap fdPredsOfInst insts @@ -190,10 +202,6 @@ must be witnessed by an actual binding; the second tells whether an instBindingRequired :: Inst -> Bool instBindingRequired (Dict _ (ClassP clas _) _) = not (isNoDictClass clas) instBindingRequired other = True - -instCanBeGeneralised :: Inst -> Bool -instCanBeGeneralised (Dict _ (ClassP clas _) _) = not (isCcallishClass clas) -instCanBeGeneralised other = True \end{code} @@ -238,11 +246,12 @@ newDictsAtLoc inst_loc theta newIPDict :: InstOrigin -> IPName Name -> Type -> TcM (IPName Id, Inst) newIPDict orig ip_name ty - = getInstLoc orig `thenM` \ inst_loc@(InstLoc _ loc _) -> + = getInstLoc orig `thenM` \ inst_loc -> newUnique `thenM` \ uniq -> let pred = IParam ip_name ty - id = mkLocalId (mkPredName uniq loc pred) (mkPredTy pred) + name = mkPredName uniq (instLocSrcLoc inst_loc) pred + id = mkLocalId name (mkPredTy pred) in returnM (mapIPName (\n -> id) ip_name, Dict id pred inst_loc) \end{code} @@ -263,7 +272,7 @@ tcInstCall orig fun_ty -- fun_ty is usually a sigma-type newDicts orig theta `thenM` \ dicts -> extendLIEs dicts `thenM_` let - inst_fn e = mkHsDictApp (mkHsTyApp e (mkTyVarTys tyvars)) (map instToId dicts) + inst_fn e = DictApp (mkHsTyApp (noLoc e) (mkTyVarTys tyvars)) (map instToId dicts) in returnM (mkCoercion inst_fn, tau) @@ -322,6 +331,11 @@ newMethodWithGivenTy orig id tys theta tau -- This is important because they are used by TcSimplify -- to simplify Insts +-- NB: the kind of the type variable to be instantiated +-- might be a sub-kind of the type to which it is applied, +-- notably when the latter is a type variable of kind ?? +-- Hence the call to checkKind +-- A worry: is this needed anywhere else? tcInstClassOp :: InstLoc -> Id -> [TcType] -> TcM Inst tcInstClassOp inst_loc sel_id tys = let @@ -330,8 +344,21 @@ tcInstClassOp inst_loc sel_id tys substTyWith tyvars tys rho (preds,tau) = tcSplitPhiTy rho_ty in + zipWithM_ checkKind tyvars tys `thenM_` newMethod inst_loc sel_id tys preds tau +checkKind :: TyVar -> TcType -> TcM () +-- Ensure that the type has a sub-kind of the tyvar +checkKind tv ty + = do { ty1 <- zonkTcType ty + ; if typeKind ty1 `isSubKind` tyVarKind tv + then return () + else do + { traceTc (text "checkKind: adding kind constraint" <+> ppr tv <+> ppr ty) + ; tv1 <- tcInstTyVar VanillaTv tv + ; unifyTauTy (mkTyVarTy tv1) ty1 }} + + --------------------------- newMethod inst_loc id tys theta tau = newUnique `thenM` \ new_uniq -> @@ -352,19 +379,15 @@ cases (the rest are caught in lookupInst). newOverloadedLit :: InstOrigin -> HsOverLit -> TcType - -> TcM TcExpr -newOverloadedLit orig lit expected_ty - = zapToType expected_ty `thenM_` - -- The expected type might be a 'hole' type variable, - -- in which case we must zap it to an ordinary type variable - new_over_lit orig lit expected_ty - -new_over_lit orig lit@(HsIntegral i fi) expected_ty - | fi /= fromIntegerName -- Do not generate a LitInst for rebindable - -- syntax. Reason: tcSyntaxName does unification + -> TcM (LHsExpr TcId) +newOverloadedLit orig lit@(HsIntegral i fi) expected_ty + | fi /= fromIntegerName -- Do not generate a LitInst for rebindable syntax. + -- Reason: tcSyntaxName does unification -- which is very inconvenient in tcSimplify - = tcSyntaxName orig expected_ty fromIntegerName fi `thenM` \ (expr, _) -> - returnM (HsApp expr (HsLit (HsInteger i))) + -- ToDo: noLoc sadness + = tcSyntaxName orig expected_ty (fromIntegerName, noLoc (HsVar fi)) `thenM` \ (_,expr) -> + mkIntegerLit i `thenM` \ integer_lit -> + returnM (mkHsApp expr integer_lit) | Just expr <- shortCutIntLit i expected_ty = returnM expr @@ -372,11 +395,11 @@ new_over_lit orig lit@(HsIntegral i fi) expected_ty | otherwise = newLitInst orig lit expected_ty -new_over_lit orig lit@(HsFractional r fr) expected_ty +newOverloadedLit orig lit@(HsFractional r fr) expected_ty | fr /= fromRationalName -- c.f. HsIntegral case - = tcSyntaxName orig expected_ty fromRationalName fr `thenM` \ (expr, _) -> - mkRatLit r `thenM` \ rat_lit -> - returnM (HsApp expr rat_lit) + = tcSyntaxName orig expected_ty (fromRationalName, noLoc (HsVar fr)) `thenM` \ (_,expr) -> + mkRatLit r `thenM` \ rat_lit -> + returnM (mkHsApp expr rat_lit) | Just expr <- shortCutFracLit r expected_ty = returnM expr @@ -384,6 +407,7 @@ new_over_lit orig lit@(HsFractional r fr) expected_ty | otherwise = newLitInst orig lit expected_ty +newLitInst :: InstOrigin -> HsOverLit -> TcType -> TcM (LHsExpr TcId) newLitInst orig lit expected_ty = getInstLoc orig `thenM` \ loc -> newUnique `thenM` \ new_uniq -> @@ -392,17 +416,17 @@ newLitInst orig lit expected_ty lit_id = mkSysLocal FSLIT("lit") new_uniq expected_ty in extendLIE lit_inst `thenM_` - returnM (HsVar (instToId lit_inst)) + returnM (L (instLocSrcSpan loc) (HsVar (instToId lit_inst))) -shortCutIntLit :: Integer -> TcType -> Maybe TcExpr +shortCutIntLit :: Integer -> TcType -> Maybe (LHsExpr TcId) -- Returns noLoc'd result :-) shortCutIntLit i ty - | isIntTy ty && inIntRange i -- Short cut for Int - = Just (HsLit (HsInt i)) - | isIntegerTy ty -- Short cut for Integer - = Just (HsLit (HsInteger i)) + | isIntTy ty && inIntRange i -- Short cut for Int + = Just (noLoc (HsLit (HsInt i))) + | isIntegerTy ty -- Short cut for Integer + = Just (noLoc (HsLit (HsInteger i ty))) | otherwise = Nothing -shortCutFracLit :: Rational -> TcType -> Maybe TcExpr +shortCutFracLit :: Rational -> TcType -> Maybe (LHsExpr TcId) -- Returns noLoc'd result :-) shortCutFracLit f ty | isFloatTy ty = Just (mkHsConApp floatDataCon [] [HsLit (HsFloatPrim f)]) @@ -410,13 +434,17 @@ shortCutFracLit f ty = Just (mkHsConApp doubleDataCon [] [HsLit (HsDoublePrim f)]) | otherwise = Nothing -mkRatLit :: Rational -> TcM TcExpr +mkIntegerLit :: Integer -> TcM (LHsExpr TcId) +mkIntegerLit i + = tcMetaTy integerTyConName `thenM` \ integer_ty -> + getSrcSpanM `thenM` \ span -> + returnM (L span $ HsLit (HsInteger i integer_ty)) + +mkRatLit :: Rational -> TcM (LHsExpr TcId) mkRatLit r - = tcLookupTyCon rationalTyConName `thenM` \ rat_tc -> - let - rational_ty = mkGenTyConApp rat_tc [] - in - returnM (HsLit (HsRat r rational_ty)) + = tcMetaTy rationalTyConName `thenM` \ rat_ty -> + getSrcSpanM `thenM` \ span -> + returnM (L span $ HsLit (HsRat r rat_ty)) \end{code} @@ -489,6 +517,16 @@ pprInst m@(Method u id tys theta tau loc) show_uniq u, ppr (instToId m) -}] + +pprDFuns :: [DFunId] -> SDoc +-- Prints the dfun as an instance declaration +pprDFuns dfuns = vcat [ hang (ppr (getSrcLoc dfun) <> colon) + 2 (ptext SLIT("instance") <+> sep [pprThetaArrow theta, + pprClassPred clas tys]) + | dfun <- dfuns + , let (_, theta, clas, tys) = tcSplitDFunTy (idType dfun) ] + -- Print without the for-all, which the programmer doesn't write + show_uniq u = ifPprDebug (text "{-" <> ppr u <> text "-}") tidyInst :: TidyEnv -> Inst -> Inst @@ -517,6 +555,72 @@ showLIE str %************************************************************************ %* * + Extending the instance environment +%* * +%************************************************************************ + +\begin{code} +tcExtendLocalInstEnv :: [DFunId] -> TcM a -> TcM a + -- Add new locally-defined instances +tcExtendLocalInstEnv dfuns thing_inside + = do { traceDFuns dfuns + ; env <- getGblEnv + ; dflags <- getDOpts + ; inst_env' <- foldlM (addInst dflags) (tcg_inst_env env) dfuns + ; let env' = env { tcg_insts = dfuns ++ tcg_insts env, + tcg_inst_env = inst_env' } + ; setGblEnv env' thing_inside } + +addInst :: DynFlags -> InstEnv -> DFunId -> TcM InstEnv +-- Check that the proposed new instance is OK, +-- and then add it to the home inst env +addInst dflags home_ie dfun + = do { -- Load imported instances, so that we report + -- duplicates correctly + pkg_ie <- loadImportedInsts cls tys + + -- Check functional dependencies + ; case checkFunDeps (pkg_ie, home_ie) dfun of + Just dfuns -> funDepErr dfun dfuns + Nothing -> return () + + -- Check for duplicate instance decls + ; let { (matches, _) = lookupInstEnv dflags (pkg_ie, home_ie) cls tys + ; dup_dfuns = [dup_dfun | (_, (_, dup_tys, dup_dfun)) <- matches, + isJust (matchTys (mkVarSet tvs) tys dup_tys)] } + -- Find memebers of the match list which + -- dfun itself matches. If the match is 2-way, it's a duplicate + ; case dup_dfuns of + dup_dfun : _ -> dupInstErr dfun dup_dfun + [] -> return () + + -- OK, now extend the envt + ; return (extendInstEnv home_ie dfun) } + where + (tvs, _, cls, tys) = tcSplitDFunTy (idType dfun) + +traceDFuns dfuns + = traceTc (text "Adding instances:" <+> vcat (map pp dfuns)) + where + pp dfun = ppr dfun <+> dcolon <+> ppr (idType dfun) + +funDepErr dfun dfuns + = addDictLoc dfun $ + addErr (hang (ptext SLIT("Functional dependencies conflict between instance declarations:")) + 2 (pprDFuns (dfun:dfuns))) +dupInstErr dfun dup_dfun + = addDictLoc dfun $ + addErr (hang (ptext SLIT("Duplicate instance declarations:")) + 2 (pprDFuns [dfun, dup_dfun])) + +addDictLoc dfun thing_inside + = addSrcSpan (mkSrcSpan loc loc) thing_inside + where + loc = getSrcLoc dfun +\end{code} + +%************************************************************************ +%* * \subsection{Looking up Insts} %* * %************************************************************************ @@ -524,8 +628,8 @@ showLIE str \begin{code} data LookupInstResult s = NoInstance - | SimpleInst TcExpr -- Just a variable, type application, or literal - | GenInst [Inst] TcExpr -- The expression and its needed insts + | SimpleInst (LHsExpr TcId) -- Just a variable, type application, or literal + | GenInst [Inst] (LHsExpr TcId) -- The expression and its needed insts lookupInst :: Inst -> TcM (LookupInstResult s) -- It's important that lookupInst does not put any new stuff into @@ -533,53 +637,13 @@ lookupInst :: Inst -> TcM (LookupInstResult s) -- the LookupInstResult, where they can be further processed by tcSimplify --- Dictionaries -lookupInst dict@(Dict _ pred@(ClassP clas tys) loc) - = getDOpts `thenM` \ dflags -> - tcGetInstEnv `thenM` \ inst_env -> - case lookupInstEnv dflags inst_env clas tys of - - FoundInst tenv dfun_id - -> -- It's possible that not all the tyvars are in - -- the substitution, tenv. For example: - -- instance C X a => D X where ... - -- (presumably there's a functional dependency in class C) - -- Hence the mk_ty_arg to instantiate any un-substituted tyvars. - getStage `thenM` \ use_stage -> - checkWellStaged (ptext SLIT("instance for") <+> quotes (ppr pred)) - (topIdLvl dfun_id) use_stage `thenM_` - traceTc (text "lookupInst" <+> ppr dfun_id <+> ppr (topIdLvl dfun_id) <+> ppr use_stage) `thenM_` - let - (tyvars, rho) = tcSplitForAllTys (idType dfun_id) - mk_ty_arg tv = case lookupSubstEnv tenv tv of - Just (DoneTy ty) -> returnM ty - Nothing -> tcInstTyVar VanillaTv tv `thenM` \ tc_tv -> - returnM (mkTyVarTy tc_tv) - in - mappM mk_ty_arg tyvars `thenM` \ ty_args -> - let - dfun_rho = substTy (mkTyVarSubst tyvars ty_args) rho - (theta, _) = tcSplitPhiTy dfun_rho - ty_app = mkHsTyApp (HsVar dfun_id) ty_args - in - if null theta then - returnM (SimpleInst ty_app) - else - newDictsAtLoc loc theta `thenM` \ dicts -> - let - rhs = mkHsDictApp ty_app (map instToId dicts) - in - returnM (GenInst dicts rhs) - - other -> returnM NoInstance - -lookupInst (Dict _ _ _) = returnM NoInstance - -- Methods lookupInst inst@(Method _ id tys theta _ loc) = newDictsAtLoc loc theta `thenM` \ dicts -> - returnM (GenInst dicts (mkHsDictApp (mkHsTyApp (HsVar id) tys) (map instToId dicts))) + returnM (GenInst dicts (mkHsDictApp (mkHsTyApp (L span (HsVar id)) tys) (map instToId dicts))) + where + span = instLocSrcSpan loc -- Literals @@ -598,9 +662,10 @@ lookupInst inst@(LitInst u (HsIntegral i from_integer_name) ty loc) = ASSERT( from_integer_name == fromIntegerName ) -- A LitInst invariant tcLookupId fromIntegerName `thenM` \ from_integer -> tcInstClassOp loc from_integer [ty] `thenM` \ method_inst -> + mkIntegerLit i `thenM` \ integer_lit -> returnM (GenInst [method_inst] - (HsApp (HsVar (instToId method_inst)) (HsLit (HsInteger i)))) - + (mkHsApp (L (instLocSrcSpan loc) + (HsVar (instToId method_inst))) integer_lit)) lookupInst inst@(LitInst u (HsFractional f from_rat_name) ty loc) | Just expr <- shortCutFracLit f ty @@ -611,7 +676,89 @@ lookupInst inst@(LitInst u (HsFractional f from_rat_name) ty loc) tcLookupId fromRationalName `thenM` \ from_rational -> tcInstClassOp loc from_rational [ty] `thenM` \ method_inst -> mkRatLit f `thenM` \ rat_lit -> - returnM (GenInst [method_inst] (HsApp (HsVar (instToId method_inst)) rat_lit)) + returnM (GenInst [method_inst] (mkHsApp (L (instLocSrcSpan loc) + (HsVar (instToId method_inst))) rat_lit)) + +-- Dictionaries +lookupInst dict@(Dict _ pred@(ClassP clas tys) loc) + = do { dflags <- getDOpts + ; if all tcIsTyVarTy tys && + not (dopt Opt_AllowUndecidableInstances dflags) + -- Common special case; no lookup + -- NB: tcIsTyVarTy... don't look through newtypes! + -- Don't take this short cut if we allow undecidable instances + -- because we might have "instance T a where ...". + -- [That means we need -fallow-undecidable-instances in the + -- client module, as well as the module with the instance decl.] + then return NoInstance + + else do + { pkg_ie <- loadImportedInsts clas tys + -- Suck in any instance decls that may be relevant + ; tcg_env <- getGblEnv + ; case lookupInstEnv dflags (pkg_ie, tcg_inst_env tcg_env) clas tys of { + ([(tenv, (_,_,dfun_id))], []) -> instantiate_dfun tenv dfun_id pred loc ; + (matches, unifs) -> do + { traceTc (text "lookupInst" <+> vcat [text "matches" <+> ppr matches, + text "unifs" <+> ppr unifs]) + ; return NoInstance } } } } + -- In the case of overlap (multiple matches) we report + -- NoInstance here. That has the effect of making the + -- context-simplifier return the dict as an irreducible one. + -- Then it'll be given to addNoInstanceErrs, which will do another + -- lookupInstEnv to get the detailed info about what went wrong. + +lookupInst (Dict _ _ _) = returnM NoInstance + +----------------- +instantiate_dfun tenv dfun_id pred loc + = -- Record that this dfun is needed + record_dfun_usage dfun_id `thenM_` + + -- It's possible that not all the tyvars are in + -- the substitution, tenv. For example: + -- instance C X a => D X where ... + -- (presumably there's a functional dependency in class C) + -- Hence the mk_ty_arg to instantiate any un-substituted tyvars. + getStage `thenM` \ use_stage -> + checkWellStaged (ptext SLIT("instance for") <+> quotes (ppr pred)) + (topIdLvl dfun_id) use_stage `thenM_` + let + (tyvars, rho) = tcSplitForAllTys (idType dfun_id) + mk_ty_arg tv = case lookupSubstEnv tenv tv of + Just (DoneTy ty) -> returnM ty + Nothing -> tcInstTyVar VanillaTv tv `thenM` \ tc_tv -> + returnM (mkTyVarTy tc_tv) + in + mappM mk_ty_arg tyvars `thenM` \ ty_args -> + let + dfun_rho = substTy (mkTyVarSubst tyvars ty_args) rho + (theta, _) = tcSplitPhiTy dfun_rho + ty_app = mkHsTyApp (L (instLocSrcSpan loc) (HsVar dfun_id)) ty_args + in + if null theta then + returnM (SimpleInst ty_app) + else + newDictsAtLoc loc theta `thenM` \ dicts -> + let + rhs = mkHsDictApp ty_app (map instToId dicts) + in + returnM (GenInst dicts rhs) + +record_dfun_usage dfun_id + | isInternalName dfun_name = return () -- From this module + | not (isHomePackageName dfun_name) = return () -- From another package package + | otherwise = getGblEnv `thenM` \ tcg_env -> + updMutVar (tcg_inst_uses tcg_env) + (`addOneToNameSet` idName dfun_id) + where + dfun_name = idName dfun_id + +tcGetInstEnvs :: TcM (InstEnv, InstEnv) +-- Gets both the home-pkg inst env (includes module being compiled) +-- and the external-package inst-env +tcGetInstEnvs = do { eps <- getEps; env <- getGblEnv; + return (tcg_inst_env env, eps_inst_env eps) } \end{code} @@ -648,27 +795,41 @@ just use the expression inline. \begin{code} tcSyntaxName :: InstOrigin -> TcType -- Type to instantiate it at - -> Name -> Name -- (Standard name, user name) - -> TcM (TcExpr, TcType) -- Suitable expression with its type + -> (Name, LHsExpr Name) -- (Standard name, user name) + -> TcM (Name, LHsExpr TcId) -- (Standard name, suitable expression) -- NB: tcSyntaxName calls tcExpr, and hence can do unification. -- So we do not call it from lookupInst, which is called from tcSimplify -tcSyntaxName orig ty std_nm user_nm +tcSyntaxName orig ty (std_nm, L span (HsVar user_nm)) | std_nm == user_nm - = newMethodFromName orig ty std_nm `thenM` \ id -> - returnM (HsVar id, idType id) + = addSrcSpan span (tcStdSyntaxName orig ty std_nm) - | otherwise +tcSyntaxName orig ty (std_nm, user_nm_expr) = tcLookupId std_nm `thenM` \ std_id -> let -- C.f. newMethodAtLoc ([tv], _, tau) = tcSplitSigmaTy (idType std_id) tau1 = substTyWith [tv] [ty] tau + -- Actually, the "tau-type" might be a sigma-type in the + -- case of locally-polymorphic methods. in - addErrCtxtM (syntaxNameCtxt user_nm orig tau1) $ - tcExpr (HsVar user_nm) tau1 `thenM` \ user_fn -> - returnM (user_fn, tau1) + addErrCtxtM (syntaxNameCtxt user_nm_expr orig tau1) $ + + -- Check that the user-supplied thing has the + -- same type as the standard one + tcCheckSigma user_nm_expr tau1 `thenM` \ expr -> + returnM (std_nm, expr) + +tcStdSyntaxName :: InstOrigin + -> TcType -- Type to instantiate it at + -> Name -- Standard name + -> TcM (Name, LHsExpr TcId) -- (Standard name, suitable expression) + +tcStdSyntaxName orig ty std_nm + = newMethodFromName orig ty std_nm `thenM` \ id -> + getSrcSpanM `thenM` \ span -> + returnM (std_nm, L span (HsVar id)) syntaxNameCtxt name orig ty tidy_env = getInstLoc orig `thenM` \ inst_loc ->