X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FInst.lhs;h=5790e7bd36213ba4c79485d847b8598bf02ca2bb;hb=16e4ce4c0c02650082f2e11982017c903c549ad5;hp=464ec76399de3116d2021d1affadcdc6c9fbf14b;hpb=3c58c25b1b99143c0ac03510423a95bc3bd41aa2;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/Inst.lhs b/ghc/compiler/typecheck/Inst.lhs index 464ec76..5790e7b 100644 --- a/ghc/compiler/typecheck/Inst.lhs +++ b/ghc/compiler/typecheck/Inst.lhs @@ -21,7 +21,7 @@ module Inst ( ipNamesOfInst, ipNamesOfInsts, fdPredsOfInst, fdPredsOfInsts, instLoc, getDictClassTys, dictPred, - lookupInst, lookupSimpleInst, LookupInstResult(..), + lookupInst, LookupInstResult(..), isDict, isClassDict, isMethod, isLinearInst, linearInstType, isIPDict, isInheritableInst, @@ -36,45 +36,44 @@ module Inst ( #include "HsVersions.h" -import {-# SOURCE #-} TcExpr( tcExpr ) +import {-# SOURCE #-} TcExpr( tcCheckSigma ) import HsSyn ( HsLit(..), HsOverLit(..), HsExpr(..) ) -import TcHsSyn ( TcExpr, TcId, TcIdSet, TypecheckedHsExpr, - mkHsTyApp, mkHsDictApp, mkHsConApp, zonkId +import TcHsSyn ( TcExpr, TcId, TcIdSet, + mkHsTyApp, mkHsDictApp, mkHsConApp, zonkId, + mkCoercion, ExprCoFn ) import TcRnMonad -import TcEnv ( tcGetInstEnv, tcLookupId, tcLookupTyCon ) +import TcEnv ( tcGetInstEnv, tcLookupId, tcLookupTyCon, checkWellStaged, topIdLvl ) import InstEnv ( InstLookupResult(..), lookupInstEnv ) -import TcMType ( zonkTcType, zonkTcTypes, zonkTcPredType, zapToType, +import TcMType ( zonkTcType, zonkTcTypes, zonkTcPredType, zonkTcThetaType, tcInstTyVar, tcInstType, tcInstTyVars ) import TcType ( Type, TcType, TcThetaType, TcTyVarSet, - SourceType(..), PredType, ThetaType, TyVarDetails(VanillaTv), + SourceType(..), PredType, TyVarDetails(VanillaTv), tcSplitForAllTys, tcSplitForAllTys, mkTyConApp, - tcSplitMethodTy, tcSplitPhiTy, mkGenTyConApp, + tcSplitPhiTy, mkGenTyConApp, 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 ) import CoreFVs ( idFreeTyVars ) -import Class ( Class ) 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 Subst ( emptyInScopeSet, mkSubst, substTy, substTyWith, substTheta, mkTyVarSubst ) +import Subst ( substTy, substTyWith, substTheta, mkTyVarSubst ) import Literal ( inIntRange ) import Var ( TyVar ) import VarEnv ( TidyEnv, emptyTidyEnv, lookupSubstEnv, SubstResult(..) ) import VarSet ( elemVarSet, emptyVarSet, unionVarSet ) import TysWiredIn ( floatDataCon, doubleDataCon ) import PrelNames( fromIntegerName, fromRationalName, rationalTyConName ) -import Util ( equalLength ) import BasicTypes( IPName(..), mapIPName, ipNameName ) import UniqSupply( uniqsFromSupply ) import Outputable @@ -102,11 +101,14 @@ 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 @@ -258,7 +260,7 @@ newIPDict orig ip_name ty \begin{code} -tcInstCall :: InstOrigin -> TcType -> TcM (TypecheckedHsExpr -> TypecheckedHsExpr, TcType) +tcInstCall :: InstOrigin -> TcType -> TcM (ExprCoFn, TcType) tcInstCall orig fun_ty -- fun_ty is usually a sigma-type = tcInstType VanillaTv fun_ty `thenM` \ (tyvars, theta, tau) -> newDicts orig theta `thenM` \ dicts -> @@ -266,7 +268,7 @@ tcInstCall orig fun_ty -- fun_ty is usually a sigma-type let inst_fn e = mkHsDictApp (mkHsTyApp e (mkTyVarTys tyvars)) (map instToId dicts) in - returnM (inst_fn, tau) + returnM (mkCoercion inst_fn, tau) tcInstDataCon :: InstOrigin -> DataCon -> TcM ([TcType], -- Types to instantiate at @@ -324,23 +326,14 @@ newMethodWithGivenTy orig id tys theta tau -- to simplify Insts tcInstClassOp :: InstLoc -> Id -> [TcType] -> TcM Inst - -- Instantiate the specified class op, but *only* with the main - -- class dictionary. For example, given 'op' defined thus: - -- class Foo a where - -- op :: (?x :: String) => a -> a - -- (tcInstClassOp op T) should return an Inst with type - -- (?x :: String) => T -> T - -- That is, the class-op's context is still there. - -- This is really important in the use of tcInstClassOp in TcClassDcls.mkMethodBind tcInstClassOp inst_loc sel_id tys = let (tyvars,rho) = tcSplitForAllTys (idType sel_id) - rho_ty = substTyWith tyvars tys rho - (pred,tau) = tcSplitMethodTy rho_ty - -- Split off exactly one predicate (see the example above) + rho_ty = ASSERT( length tyvars == length tys ) + substTyWith tyvars tys rho + (preds,tau) = tcSplitPhiTy rho_ty in - ASSERT( isClassPred pred ) - newMethod inst_loc sel_id tys [pred] tau + newMethod inst_loc sel_id tys preds tau --------------------------- newMethod inst_loc id tys theta tau @@ -367,7 +360,7 @@ 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, _) -> + = tcSyntaxName orig expected_ty (fromIntegerName, HsVar fi) `thenM` \ (_,expr) -> returnM (HsApp expr (HsLit (HsInteger i))) | Just expr <- shortCutIntLit i expected_ty @@ -378,8 +371,8 @@ newOverloadedLit orig lit@(HsIntegral i fi) 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 -> + = tcSyntaxName orig expected_ty (fromRationalName, HsVar fr) `thenM` \ (_,expr) -> + mkRatLit r `thenM` \ rat_lit -> returnM (HsApp expr rat_lit) | Just expr <- shortCutFracLit r expected_ty @@ -391,9 +384,6 @@ newOverloadedLit orig lit@(HsFractional r fr) expected_ty newLitInst orig lit expected_ty = getInstLoc orig `thenM` \ loc -> newUnique `thenM` \ new_uniq -> - 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 let lit_inst = LitInst lit_id lit expected_ty loc lit_id = mkSysLocal FSLIT("lit") new_uniq expected_ty @@ -481,7 +471,7 @@ pprInsts insts = parens (sep (punctuate comma (map pprInst insts))) pprInstsInFull insts = vcat (map go insts) where - go inst = quotes (ppr inst) <+> pprInstLoc (instLoc inst) + go inst = sep [quotes (ppr inst), nest 2 (pprInstLoc (instLoc inst))] pprInst (LitInst u lit ty loc) = hsep [ppr lit, ptext SLIT("at"), ppr ty, show_uniq u] @@ -514,11 +504,11 @@ tidyMoreInsts env insts tidyInsts :: [Inst] -> (TidyEnv, [Inst]) tidyInsts insts = tidyMoreInsts emptyTidyEnv insts -showLIE :: String -> TcM () -- Debugging +showLIE :: SDoc -> TcM () -- Debugging showLIE str = do { lie_var <- getLIEVar ; lie <- readMutVar lie_var ; - traceTc (text str <+> pprInstsInFull (lieToList lie)) } + traceTc (str <+> pprInstsInFull (lieToList lie)) } \end{code} @@ -541,7 +531,7 @@ lookupInst :: Inst -> TcM (LookupInstResult s) -- Dictionaries -lookupInst dict@(Dict _ (ClassP clas tys) loc) +lookupInst dict@(Dict _ pred@(ClassP clas tys) loc) = getDOpts `thenM` \ dflags -> tcGetInstEnv `thenM` \ inst_env -> case lookupInstEnv dflags inst_env clas tys of @@ -552,6 +542,10 @@ lookupInst dict@(Dict _ (ClassP clas tys) loc) -- 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 @@ -617,28 +611,6 @@ lookupInst inst@(LitInst u (HsFractional f from_rat_name) ty loc) returnM (GenInst [method_inst] (HsApp (HsVar (instToId method_inst)) rat_lit)) \end{code} -There is a second, simpler interface, when you want an instance of a -class at a given nullary type constructor. It just returns the -appropriate dictionary if it exists. It is used only when resolving -ambiguous dictionaries. - -\begin{code} -lookupSimpleInst :: Class - -> [Type] -- Look up (c,t) - -> TcM (Maybe ThetaType) -- Here are the needed (c,t)s - -lookupSimpleInst clas tys - = getDOpts `thenM` \ dflags -> - tcGetInstEnv `thenM` \ inst_env -> - case lookupInstEnv dflags inst_env clas tys of - FoundInst tenv dfun - -> returnM (Just (substTheta (mkSubst emptyInScopeSet tenv) theta)) - where - (_, rho) = tcSplitForAllTys (idType dfun) - (theta,_) = tcSplitPhiTy rho - - other -> returnM Nothing -\end{code} %************************************************************************ @@ -673,27 +645,29 @@ 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, HsExpr Name) -- (Standard name, user name) + -> TcM (Name, TcExpr) -- (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, HsVar user_nm) | std_nm == user_nm = newMethodFromName orig ty std_nm `thenM` \ id -> - returnM (HsVar id, idType id) + returnM (std_nm, HsVar id) - | 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) $ + tcCheckSigma user_nm_expr tau1 `thenM` \ expr -> + returnM (std_nm, expr) syntaxNameCtxt name orig ty tidy_env = getInstLoc orig `thenM` \ inst_loc ->