X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FInst.lhs;h=7cb4a7fd6c2f49315ce9b41bdd8d8ca6910e5c8d;hb=e0a56725a120bd0ce5807dddc0c56a1d02eb01f3;hp=fd242812a52b6bc88db6d80bc0cb9f88a4be2119;hpb=7b0181919416d8f04324575b7e17031ca692f5b0;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/Inst.lhs b/ghc/compiler/typecheck/Inst.lhs index fd24281..7cb4a7f 100644 --- a/ghc/compiler/typecheck/Inst.lhs +++ b/ghc/compiler/typecheck/Inst.lhs @@ -1,68 +1,81 @@ % -% (c) The GRASP/AQUA Project, Glasgow University, 1992-1996 +% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998 % \section[Inst]{The @Inst@ type: dictionaries or method instances} \begin{code} -#include "HsVersions.h" - -module Inst ( - Inst(..), -- Visible only to TcSimplify +module Inst ( + LIE, emptyLIE, unitLIE, plusLIE, consLIE, zonkLIE, + plusLIEs, mkLIE, isEmptyLIE, lieToList, listToLIE, - InstOrigin(..), OverloadedLit(..), - LIE(..), emptyLIE, unitLIE, plusLIE, consLIE, zonkLIE, plusLIEs, + Inst, + pprInst, pprInsts, pprInstsInFull, tidyInsts, tidyMoreInsts, - InstanceMapper(..), + newDictsFromOld, newDicts, cloneDict, + newMethod, newMethodFromName, newMethodWithGivenTy, newMethodAtLoc, + newOverloadedLit, newIPDict, tcInstCall, tcInstDataCon, - newDicts, newDictsAtLoc, newMethod, newMethodWithGivenTy, newOverloadedLit, + tyVarsOfInst, tyVarsOfInsts, tyVarsOfLIE, + ipNamesOfInst, ipNamesOfInsts, predsOfInst, predsOfInsts, + instLoc, getDictClassTys, dictPred, - instType, tyVarsOfInst, lookupInst, + lookupInst, lookupSimpleInst, LookupInstResult(..), - isDict, isTyVarDict, + isDict, isClassDict, isMethod, + isLinearInst, linearInstType, + isTyVarDict, isStdClassTyVarDict, isMethodFor, + instBindingRequired, instCanBeGeneralised, - zonkInst, instToId, - - matchesInst, - instBindingRequired, instCanBeGeneralised + zonkInst, zonkInsts, + instToId, instName, + InstOrigin(..), InstLoc, pprInstLoc ) where -import Ubiq - -import HsSyn ( HsLit(..), HsExpr(..), HsBinds, - InPat, OutPat, Stmt, Qual, Match, - ArithSeqInfo, PolyType, Fake ) -import RnHsSyn ( RenamedArithSeqInfo(..), RenamedHsExpr(..) ) -import TcHsSyn ( TcIdOcc(..), TcExpr(..), TcIdBndr(..), - mkHsTyApp, mkHsDictApp ) +#include "HsVersions.h" +import HsSyn ( HsLit(..), HsOverLit(..), HsExpr(..) ) +import TcHsSyn ( TcExpr, TcId, TypecheckedHsExpr, + mkHsTyApp, mkHsDictApp, mkHsConApp, zonkId + ) import TcMonad -import TcEnv ( tcLookupGlobalValueByKey ) -import TcType ( TcType(..), TcRhoType(..), TcMaybe, TcTyVarSet(..), - tcInstType, tcInstTcType, zonkTcType ) - -import Bag ( emptyBag, unitBag, unionBags, unionManyBags, listToBag, consBag ) -import Class ( Class(..), GenClass, ClassInstEnv(..), getClassInstEnv ) -import Id ( GenId, idType, mkInstId ) -import MatchEnv ( lookupMEnv, insertMEnv ) -import Name ( mkLocalName, getLocalName, Name ) +import TcEnv ( TcIdSet, tcGetInstEnv, tcLookupId ) +import InstEnv ( InstLookupResult(..), lookupInstEnv ) +import TcMType ( zonkTcType, zonkTcTypes, zonkTcPredType, zapToType, + zonkTcThetaType, tcInstTyVar, tcInstType, tcInstTyVars + ) +import TcType ( Type, TcType, TcThetaType, TcPredType, TcTauType, TcTyVarSet, + SourceType(..), PredType, ThetaType, TyVarDetails(VanillaTv), + tcSplitForAllTys, tcSplitForAllTys, mkTyConApp, + tcSplitMethodTy, tcSplitPhiTy, tcFunArgTy, + isIntTy,isFloatTy, isIntegerTy, isDoubleTy, + tcIsTyVarTy, mkPredTy, mkTyVarTy, mkTyVarTys, + tyVarsOfType, tyVarsOfTypes, tyVarsOfPred, tidyPred, + isClassPred, isTyVarClassPred, isLinearPred, + getClassPredTys, getClassPredTys_maybe, mkPredName, + tidyType, tidyTypes, tidyFreeTyVars, + tcCmpType, tcCmpTypes, tcCmpPred + ) +import CoreFVs ( idFreeTyVars ) +import Class ( Class ) +import 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, mkTopTyVarSubst + ) +import Literal ( inIntRange ) +import VarEnv ( TidyEnv, lookupSubstEnv, SubstResult(..) ) +import VarSet ( elemVarSet, emptyVarSet, unionVarSet ) +import TysWiredIn ( floatDataCon, doubleDataCon ) +import PrelNames( fromIntegerName, fromRationalName ) +import Util ( thenCmp, equalLength ) +import BasicTypes( IPName(..), mapIPName, ipNameName ) + +import Bag import Outputable -import PprType ( GenClass, TyCon, GenType, GenTyVar ) -import PprStyle ( PprStyle(..) ) -import Pretty -import RnHsSyn ( RnName{-instance NamedThing-} ) -import SpecEnv ( SpecEnv(..) ) -import SrcLoc ( SrcLoc, mkUnknownSrcLoc ) -import Type ( GenType, eqSimpleTy, - isTyVarTy, mkDictTy, splitForAllTy, splitSigmaTy, - splitRhoTy, matchTy, tyVarsOfType, tyVarsOfTypes ) -import TyVar ( GenTyVar ) -import TysPrim ( intPrimTy ) -import TysWiredIn ( intDataCon ) -import Unique ( Unique, showUnique, - fromRationalClassOpKey, fromIntClassOpKey, fromIntegerClassOpKey ) -import Util ( panic, zipEqual, zipWithEqual, assoc, assertPanic ) - \end{code} %************************************************************************ @@ -72,16 +85,29 @@ import Util ( panic, zipEqual, zipWithEqual, assoc, assertPanic ) %************************************************************************ \begin{code} -type LIE s = Bag (Inst s) +type LIE = Bag Inst +isEmptyLIE = isEmptyBag emptyLIE = emptyBag unitLIE inst = unitBag inst +mkLIE insts = listToBag insts plusLIE lie1 lie2 = lie1 `unionBags` lie2 consLIE inst lie = inst `consBag` lie plusLIEs lies = unionManyBags lies +lieToList = bagToList +listToLIE = listToBag -zonkLIE :: LIE s -> NF_TcM s (LIE s) +zonkLIE :: LIE -> NF_TcM LIE zonkLIE lie = mapBagNF_Tc zonkInst lie + +pprInsts :: [Inst] -> SDoc +pprInsts insts = parens (sep (punctuate comma (map pprInst insts))) + + +pprInstsInFull insts + = vcat (map go insts) + where + go inst = quotes (ppr inst) <+> pprInstLoc (instLoc inst) \end{code} %************************************************************************ @@ -99,216 +125,163 @@ type Int, represented by Method 34 doubleId [Int] origin \begin{code} -data Inst s +data Inst = Dict - Unique - Class -- The type of the dict is (c t), where - (TcType s) -- c is the class and t the type; - (InstOrigin s) - SrcLoc + Id + TcPredType + InstLoc | Method - Unique + Id - (TcIdOcc s) -- The overloaded function + TcId -- The overloaded function -- This function will be a global, local, or ClassOpId; -- inside instance decls (only) it can also be an InstId! -- The id needn't be completely polymorphic. -- You'll probably find its name (for documentation purposes) -- inside the InstOrigin - [TcType s] -- The types to which its polymorphic tyvars + [TcType] -- The types to which its polymorphic tyvars -- should be instantiated. -- These types must saturate the Id's foralls. - (TcRhoType s) -- Cached: (type-of-id applied to inst_tys) - -- If this type is (theta => tau) then the type of the Method - -- is tau, and the method can be built by saying - -- id inst_tys dicts - -- where dicts are constructed from theta + TcThetaType -- The (types of the) dictionaries to which the function + -- must be applied to get the method - (InstOrigin s) - SrcLoc + TcTauType -- The type of the method - | LitInst - Unique - OverloadedLit - (TcType s) -- The type at which the literal is used - (InstOrigin s) -- Always a literal; but more convenient to carry this around - SrcLoc - -data OverloadedLit - = OverloadedIntegral Integer -- The number - | OverloadedFractional Rational -- The number - -getInstOrigin (Dict u clas ty origin loc) = origin -getInstOrigin (Method u clas ty rho origin loc) = origin -getInstOrigin (LitInst u lit ty origin loc) = origin -\end{code} + InstLoc -Construction -~~~~~~~~~~~~ + -- INVARIANT: in (Method u f tys theta tau loc) + -- type of (f tys dicts(from theta)) = tau -\begin{code} -newDicts :: InstOrigin s - -> [(Class, TcType s)] - -> NF_TcM s (LIE s, [TcIdOcc s]) -newDicts orig theta - = tcGetSrcLoc `thenNF_Tc` \ loc -> - tcGetUniques (length theta) `thenNF_Tc` \ new_uniqs -> - let - mk_dict u (clas, ty) = Dict u clas ty orig loc - dicts = zipWithEqual mk_dict new_uniqs theta - in - returnNF_Tc (listToBag dicts, map instToId dicts) - -newDictsAtLoc orig loc theta -- Local function, similar to newDicts, - -- but with slightly different interface - = tcGetUniques (length theta) `thenNF_Tc` \ new_uniqs -> - let - mk_dict u (clas, ty) = Dict u clas ty orig loc - dicts = zipWithEqual mk_dict new_uniqs theta - in - returnNF_Tc (dicts, map instToId dicts) - -newMethod :: InstOrigin s - -> TcIdOcc s - -> [TcType s] - -> NF_TcM s (LIE s, TcIdOcc s) -newMethod orig id tys - = -- Get the Id type and instantiate it at the specified types - (case id of - RealId id -> let (tyvars, rho) = splitForAllTy (idType id) - in tcInstType (tyvars `zipEqual` tys) rho - TcId id -> let (tyvars, rho) = splitForAllTy (idType id) - in tcInstTcType (tyvars `zipEqual` tys) rho - ) `thenNF_Tc` \ rho_ty -> - - -- Our friend does the rest - newMethodWithGivenTy orig id tys rho_ty - - -newMethodWithGivenTy orig id tys rho_ty - = tcGetSrcLoc `thenNF_Tc` \ loc -> - tcGetUnique `thenNF_Tc` \ new_uniq -> - let - meth_inst = Method new_uniq id tys rho_ty orig loc - in - returnNF_Tc (unitLIE meth_inst, instToId meth_inst) - -newMethodAtLoc :: InstOrigin s -> SrcLoc -> Id -> [TcType s] -> NF_TcM s (Inst s, TcIdOcc s) -newMethodAtLoc orig loc real_id tys -- Local function, similar to newMethod but with - -- slightly different interface - = -- Get the Id type and instantiate it at the specified types - let - (tyvars,rho) = splitForAllTy (idType real_id) - in - tcInstType (tyvars `zipEqual` tys) rho `thenNF_Tc` \ rho_ty -> - tcGetUnique `thenNF_Tc` \ new_uniq -> - let - meth_inst = Method new_uniq (RealId real_id) tys rho_ty orig loc - in - returnNF_Tc (meth_inst, instToId meth_inst) - -newOverloadedLit :: InstOrigin s - -> OverloadedLit - -> TcType s - -> NF_TcM s (LIE s, TcIdOcc s) -newOverloadedLit orig lit ty - = tcGetSrcLoc `thenNF_Tc` \ loc -> - tcGetUnique `thenNF_Tc` \ new_uniq -> - let - lit_inst = LitInst new_uniq lit ty orig loc - in - returnNF_Tc (unitLIE lit_inst, instToId lit_inst) + | LitInst + Id + HsOverLit -- The literal from the occurrence site + TcType -- The type at which the literal is used + InstLoc \end{code} +Ordering +~~~~~~~~ +@Insts@ are ordered by their class/type info, rather than by their +unique. This allows the context-reduction mechanism to use standard finite +maps to do their stuff. \begin{code} -instToId :: Inst s -> TcIdOcc s -instToId (Dict u clas ty orig loc) - = TcId (mkInstId u (mkDictTy clas ty) (mkLocalName u SLIT("dict") loc)) -instToId (Method u id tys rho_ty orig loc) - = TcId (mkInstId u tau_ty (mkLocalName u (getLocalName id) loc)) - where - (_, tau_ty) = splitRhoTy rho_ty -- NB The method Id has just the tau type -instToId (LitInst u list ty orig loc) - = TcId (mkInstId u ty (mkLocalName u SLIT("lit") loc)) -\end{code} +instance Ord Inst where + compare = cmpInst -\begin{code} -instType :: Inst s -> TcType s -instType (Dict _ clas ty _ _) = mkDictTy clas ty -instType (LitInst _ _ ty _ _) = ty -instType (Method _ id tys ty _ _) = ty -\end{code} +instance Eq Inst where + (==) i1 i2 = case i1 `cmpInst` i2 of + EQ -> True + other -> False +cmpInst (Dict _ pred1 _) (Dict _ pred2 _) = pred1 `tcCmpPred` pred2 +cmpInst (Dict _ _ _) other = LT -Zonking -~~~~~~~ -Zonking makes sure that the instance types are fully zonked, -but doesn't do the same for the Id in a Method. There's no -need, and it's a lot of extra work. +cmpInst (Method _ _ _ _ _ _) (Dict _ _ _) = GT +cmpInst (Method _ id1 tys1 _ _ _) (Method _ id2 tys2 _ _ _) = (id1 `compare` id2) `thenCmp` (tys1 `tcCmpTypes` tys2) +cmpInst (Method _ _ _ _ _ _) other = LT -\begin{code} -zonkInst :: Inst s -> NF_TcM s (Inst s) -zonkInst (Dict u clas ty orig loc) - = zonkTcType ty `thenNF_Tc` \ new_ty -> - returnNF_Tc (Dict u clas new_ty orig loc) - -zonkInst (Method u id tys rho orig loc) -- Doesn't zonk the id! - = mapNF_Tc zonkTcType tys `thenNF_Tc` \ new_tys -> - zonkTcType rho `thenNF_Tc` \ new_rho -> - returnNF_Tc (Method u id new_tys new_rho orig loc) +cmpInst (LitInst _ lit1 ty1 _) (LitInst _ lit2 ty2 _) = (lit1 `compare` lit2) `thenCmp` (ty1 `tcCmpType` ty2) +cmpInst (LitInst _ _ _ _) other = GT -zonkInst (LitInst u lit ty orig loc) - = zonkTcType ty `thenNF_Tc` \ new_ty -> - returnNF_Tc (LitInst u lit new_ty orig loc) +-- and they can only have HsInt or HsFracs in them. \end{code} +Selection +~~~~~~~~~ \begin{code} -tyVarsOfInst :: Inst s -> TcTyVarSet s -tyVarsOfInst (Dict _ _ ty _ _) = tyVarsOfType ty -tyVarsOfInst (Method _ _ tys rho _ _) = tyVarsOfTypes tys -tyVarsOfInst (LitInst _ _ ty _ _) = tyVarsOfType ty +instName :: Inst -> Name +instName inst = idName (instToId inst) + +instToId :: Inst -> TcId +instToId (Dict id _ _) = id +instToId (Method id _ _ _ _ _) = id +instToId (LitInst id _ _ _) = id + +instLoc (Dict _ _ loc) = loc +instLoc (Method _ _ _ _ _ loc) = loc +instLoc (LitInst _ _ _ loc) = loc + +dictPred (Dict _ pred _ ) = pred +dictPred inst = pprPanic "dictPred" (ppr inst) + +getDictClassTys (Dict _ pred _) = getClassPredTys pred + +predsOfInsts :: [Inst] -> [PredType] +predsOfInsts insts = concatMap predsOfInst insts + +predsOfInst (Dict _ pred _) = [pred] +predsOfInst (Method _ _ _ theta _ _) = theta +predsOfInst (LitInst _ _ _ _) = [] + -- The last case is is really a big cheat + -- LitInsts to give rise to a (Num a) or (Fractional a) predicate + -- But Num and Fractional have only one parameter and no functional + -- dependencies, so I think no caller of predsOfInst will care. + +ipNamesOfInsts :: [Inst] -> [Name] +ipNamesOfInst :: Inst -> [Name] +-- Get the implicit parameters mentioned by these Insts +-- NB: ?x and %x get different Names + +ipNamesOfInsts insts = [n | inst <- insts, n <- ipNamesOfInst inst] + +ipNamesOfInst (Dict _ (IParam n _) _) = [ipNameName n] +ipNamesOfInst (Method _ _ _ theta _ _) = [ipNameName n | IParam n _ <- theta] +ipNamesOfInst other = [] + +tyVarsOfInst :: Inst -> TcTyVarSet +tyVarsOfInst (LitInst _ _ ty _) = tyVarsOfType ty +tyVarsOfInst (Dict _ pred _) = tyVarsOfPred pred +tyVarsOfInst (Method _ id tys _ _ _) = tyVarsOfTypes tys `unionVarSet` idFreeTyVars id + -- The id might have free type variables; in the case of + -- locally-overloaded class methods, for example + +tyVarsOfInsts insts = foldr (unionVarSet . tyVarsOfInst) emptyVarSet insts +tyVarsOfLIE lie = tyVarsOfInsts (lieToList lie) \end{code} -@matchesInst@ checks when two @Inst@s are instances of the same -thing at the same type, even if their uniques differ. - +Predicates +~~~~~~~~~~ \begin{code} -matchesInst :: Inst s -> Inst s -> Bool +isDict :: Inst -> Bool +isDict (Dict _ _ _) = True +isDict other = False -matchesInst (Dict _ clas1 ty1 _ _) (Dict _ clas2 ty2 _ _) - = clas1 == clas2 && ty1 `eqSimpleTy` ty2 +isClassDict :: Inst -> Bool +isClassDict (Dict _ pred _) = isClassPred pred +isClassDict other = False -matchesInst (Method _ id1 tys1 _ _ _) (Method _ id2 tys2 _ _ _) - = id1 == id2 - && and (zipWith eqSimpleTy tys1 tys2) - && length tys1 == length tys2 +isTyVarDict :: Inst -> Bool +isTyVarDict (Dict _ pred _) = isTyVarClassPred pred +isTyVarDict other = False -matchesInst (LitInst _ lit1 ty1 _ _) (LitInst _ lit2 ty2 _ _) - = lit1 `eq` lit2 && ty1 `eqSimpleTy` ty2 - where - (OverloadedIntegral i1) `eq` (OverloadedIntegral i2) = i1 == i2 - (OverloadedFractional f1) `eq` (OverloadedFractional f2) = f1 == f2 - _ `eq` _ = False +isMethod :: Inst -> Bool +isMethod (Method _ _ _ _ _ _) = True +isMethod other = False -matchesInst other1 other2 = False -\end{code} +isMethodFor :: TcIdSet -> Inst -> Bool +isMethodFor ids (Method uniq id tys _ _ loc) = id `elemVarSet` ids +isMethodFor ids inst = False +isLinearInst :: Inst -> Bool +isLinearInst (Dict _ pred _) = isLinearPred pred +isLinearInst other = False + -- We never build Method Insts that have + -- linear implicit paramters in them. + -- Hence no need to look for Methods + -- See TcExpr.tcId -Predicates -~~~~~~~~~~ -\begin{code} -isDict :: Inst s -> Bool -isDict (Dict _ _ _ _ _) = True -isDict other = False +linearInstType :: Inst -> TcType -- %x::t --> t +linearInstType (Dict _ (IParam _ ty) _) = ty -isTyVarDict :: Inst s -> Bool -isTyVarDict (Dict _ _ ty _ _) = isTyVarTy ty -isTyVarDict other = False + +isStdClassTyVarDict (Dict _ pred _) = case getClassPredTys_maybe pred of + Just (clas, [ty]) -> isStandardClass clas && tcIsTyVarTy ty + other -> False \end{code} Two predicates which deal with the case where class constraints don't @@ -317,338 +290,390 @@ must be witnessed by an actual binding; the second tells whether an @Inst@ can be generalised over. \begin{code} -instBindingRequired :: Inst s -> Bool -instBindingRequired inst - = case getInstOrigin inst of - CCallOrigin _ _ -> False -- No binding required - LitLitOrigin _ -> False - OccurrenceOfCon _ -> False - other -> True - -instCanBeGeneralised :: Inst s -> Bool -instCanBeGeneralised inst - = case getInstOrigin inst of - CCallOrigin _ _ -> False -- Can't be generalised - LitLitOrigin _ -> False -- Can't be generalised - other -> True -\end{code} +instBindingRequired :: Inst -> Bool +instBindingRequired (Dict _ (ClassP clas _) _) = not (isNoDictClass clas) +instBindingRequired other = True - -Printing -~~~~~~~~ -ToDo: improve these pretty-printing things. The ``origin'' is really only -relevant in error messages. - -\begin{code} -instance Outputable (Inst s) where - ppr sty (LitInst uniq lit ty orig loc) - = ppHang (ppSep [case lit of - OverloadedIntegral i -> ppInteger i - OverloadedFractional f -> ppRational f, - ppStr "at", - ppr sty ty, - show_uniq sty uniq - ]) - 4 (show_origin sty orig) - - ppr sty (Dict uniq clas ty orig loc) - = ppHang (ppSep [ppr sty clas, - ppStr "at", - ppr sty ty, - show_uniq sty uniq - ]) - 4 (show_origin sty orig) - - ppr sty (Method uniq id tys rho orig loc) - = ppHang (ppSep [ppr sty id, - ppStr "at", - ppr sty tys, - show_uniq sty uniq - ]) - 4 (show_origin sty orig) - -show_uniq PprDebug uniq = ppr PprDebug uniq -show_uniq sty uniq = ppNil - -show_origin sty orig = ppBesides [ppLparen, pprOrigin sty orig, ppRparen] +instCanBeGeneralised :: Inst -> Bool +instCanBeGeneralised (Dict _ (ClassP clas _) _) = not (isCcallishClass clas) +instCanBeGeneralised other = True \end{code} -Printing in error messages - -\begin{code} -noInstanceErr inst sty = ppHang (ppPStr SLIT("No instance for:")) 4 (ppr sty inst) -\end{code} %************************************************************************ %* * -\subsection[InstEnv-types]{Type declarations} +\subsection{Building dictionaries} %* * %************************************************************************ \begin{code} -type InstanceMapper = Class -> (ClassInstEnv, ClassOp -> SpecEnv) -\end{code} - -A @ClassInstEnv@ lives inside a class, and identifies all the instances -of that class. The @Id@ inside a ClassInstEnv mapping is the dfun for -that instance. - -There is an important consistency constraint between the @MatchEnv@s -in and the dfun @Id@s inside them: the free type variables of the -@Type@ key in the @MatchEnv@ must be a subset of the universally-quantified -type variables of the dfun. 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. - -\begin{code} -lookupInst :: Inst s - -> TcM s ([Inst s], - (TcIdOcc s, TcExpr s)) -- The new binding - --- Dictionaries - -lookupInst dict@(Dict _ clas ty orig loc) - = case lookupMEnv matchTy (get_inst_env clas orig) ty of - Nothing -> failTc (noInstanceErr dict) - - Just (dfun_id, tenv) - -> let - (tyvars, rho) = splitForAllTy (idType dfun_id) - ty_args = map (assoc "lookupInst" tenv) tyvars - -- tenv should bind all the tyvars - in - tcInstType tenv rho `thenNF_Tc` \ dfun_rho -> - let - (theta, tau) = splitRhoTy dfun_rho - in - newDictsAtLoc orig loc theta `thenNF_Tc` \ (dicts, dict_ids) -> - let - rhs = mkHsDictApp (mkHsTyApp (HsVar (RealId dfun_id)) ty_args) dict_ids - in - returnTc (dicts, (instToId dict, rhs)) - - --- Methods - -lookupInst inst@(Method _ id tys rho orig loc) - = newDictsAtLoc orig loc theta `thenNF_Tc` \ (dicts, dict_ids) -> - returnTc (dicts, (instToId inst, mkHsDictApp (mkHsTyApp (HsVar id) tys) dict_ids)) - where - (theta,_) = splitRhoTy rho - --- Literals - -lookupInst inst@(LitInst u (OverloadedIntegral i) ty orig loc) - | i >= toInteger minInt && i <= toInteger maxInt - = -- It's overloaded but small enough to fit into an Int - tcLookupGlobalValueByKey fromIntClassOpKey `thenNF_Tc` \ from_int -> - newMethodAtLoc orig loc from_int [ty] `thenNF_Tc` \ (method_inst, method_id) -> - returnTc ([method_inst], (instToId inst, HsApp (HsVar method_id) int_lit)) - - | otherwise - = -- Alas, it is overloaded and a big literal! - tcLookupGlobalValueByKey fromIntegerClassOpKey `thenNF_Tc` \ from_integer -> - newMethodAtLoc orig loc from_integer [ty] `thenNF_Tc` \ (method_inst, method_id) -> - returnTc ([method_inst], (instToId inst, HsApp (HsVar method_id) (HsLitOut (HsInt i) ty))) +newDicts :: InstOrigin + -> TcThetaType + -> NF_TcM [Inst] +newDicts orig theta + = tcGetInstLoc orig `thenNF_Tc` \ loc -> + newDictsAtLoc loc theta + +cloneDict :: Inst -> NF_TcM Inst +cloneDict (Dict id ty loc) = tcGetUnique `thenNF_Tc` \ uniq -> + returnNF_Tc (Dict (setIdUnique id uniq) ty loc) + +newDictsFromOld :: Inst -> TcThetaType -> NF_TcM [Inst] +newDictsFromOld (Dict _ _ loc) theta = newDictsAtLoc loc theta + +-- Local function, similar to newDicts, +-- but with slightly different interface +newDictsAtLoc :: InstLoc + -> TcThetaType + -> NF_TcM [Inst] +newDictsAtLoc inst_loc@(_,loc,_) theta + = tcGetUniques `thenNF_Tc` \ new_uniqs -> + returnNF_Tc (zipWith mk_dict new_uniqs theta) where - intprim_lit = HsLitOut (HsIntPrim i) intPrimTy - int_lit = HsApp (HsVar (RealId intDataCon)) intprim_lit - -lookupInst inst@(LitInst u (OverloadedFractional f) ty orig loc) - = tcLookupGlobalValueByKey fromRationalClassOpKey `thenNF_Tc` \ from_rational -> - newMethodAtLoc orig loc from_rational [ty] `thenNF_Tc` \ (method_inst, method_id) -> - returnTc ([method_inst], (instToId inst, HsApp (HsVar method_id) (HsLitOut (HsFrac f) ty))) + mk_dict uniq pred = Dict (mkLocalId (mkPredName uniq loc pred) (mkPredTy pred)) pred inst_loc + +-- For vanilla implicit parameters, there is only one in scope +-- at any time, so we used to use the name of the implicit parameter itself +-- But with splittable implicit parameters there may be many in +-- scope, so we make up a new name. +newIPDict :: InstOrigin -> IPName Name -> Type + -> NF_TcM (IPName Id, Inst) +newIPDict orig ip_name ty + = tcGetInstLoc orig `thenNF_Tc` \ inst_loc@(_,loc,_) -> + tcGetUnique `thenNF_Tc` \ uniq -> + let + pred = IParam ip_name ty + id = mkLocalId (mkPredName uniq loc pred) (mkPredTy pred) + in + returnNF_Tc (mapIPName (\n -> id) ip_name, Dict id pred inst_loc) \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} -lookupClassInstAtSimpleType :: Class -> Type -> Maybe Id - -lookupClassInstAtSimpleType clas ty - = case (lookupMEnv matchTy (getClassInstEnv clas) ty) of - Nothing -> Nothing - Just (dfun,_) -> ASSERT( null tyvars && null theta ) - Just dfun - where - (tyvars, theta, _) = splitSigmaTy (idType dfun) -\end{code} +%************************************************************************ +%* * +\subsection{Building methods (calls of overloaded functions)} +%* * +%************************************************************************ -@mkInstSpecEnv@ is used to construct the @SpecEnv@ for a dfun. -It does it by filtering the class's @InstEnv@. All pretty shady stuff. \begin{code} -mkInstSpecEnv clas inst_ty inst_tvs inst_theta = panic "mkInstSpecEnv" +tcInstCall :: InstOrigin -> TcType -> NF_TcM (TypecheckedHsExpr -> TypecheckedHsExpr, LIE, TcType) +tcInstCall orig fun_ty -- fun_ty is usually a sigma-type + = tcInstType VanillaTv fun_ty `thenNF_Tc` \ (tyvars, theta, tau) -> + newDicts orig theta `thenNF_Tc` \ dicts -> + let + inst_fn e = mkHsDictApp (mkHsTyApp e (mkTyVarTys tyvars)) (map instToId dicts) + in + returnNF_Tc (inst_fn, mkLIE dicts, tau) + +tcInstDataCon orig data_con + = let + (tvs, stupid_theta, ex_tvs, ex_theta, arg_tys, tycon) = dataConSig data_con + -- We generate constraints for the stupid theta even when + -- pattern matching (as the Report requires) + in + tcInstTyVars VanillaTv (tvs ++ ex_tvs) `thenNF_Tc` \ (all_tvs', ty_args', tenv) -> + let + stupid_theta' = substTheta tenv stupid_theta + ex_theta' = substTheta tenv ex_theta + arg_tys' = map (substTy tenv) arg_tys + + n_normal_tvs = length tvs + ex_tvs' = drop n_normal_tvs all_tvs' + result_ty = mkTyConApp tycon (take n_normal_tvs ty_args') + in + newDicts orig stupid_theta' `thenNF_Tc` \ stupid_dicts -> + newDicts orig ex_theta' `thenNF_Tc` \ ex_dicts -> + + -- Note that we return the stupid theta *only* in the LIE; + -- we don't otherwise use it at all + returnNF_Tc (ty_args', map instToId ex_dicts, arg_tys', result_ty, + mkLIE stupid_dicts, mkLIE ex_dicts, ex_tvs') + + +newMethodFromName :: InstOrigin -> TcType -> Name -> NF_TcM Inst +newMethodFromName origin ty name + = tcLookupId name `thenNF_Tc` \ id -> + -- Use tcLookupId not tcLookupGlobalId; the method is almost + -- always a class op, but with -fno-implicit-prelude GHC is + -- meant to find whatever thing is in scope, and that may + -- be an ordinary function. + newMethod origin id [ty] + +newMethod :: InstOrigin + -> TcId + -> [TcType] + -> NF_TcM Inst +newMethod orig id tys + = -- Get the Id type and instantiate it at the specified types + let + (tyvars, rho) = tcSplitForAllTys (idType id) + rho_ty = substTyWith tyvars tys rho + (pred, tau) = tcSplitMethodTy rho_ty + in + newMethodWithGivenTy orig id tys [pred] tau + +newMethodWithGivenTy orig id tys theta tau + = tcGetInstLoc orig `thenNF_Tc` \ loc -> + newMethodWith loc id tys theta tau + +newMethodWith inst_loc@(_,loc,_) id tys theta tau + = tcGetUnique `thenNF_Tc` \ new_uniq -> + let + meth_id = mkUserLocal (mkMethodOcc (getOccName id)) new_uniq tau loc + in + returnNF_Tc (Method meth_id id tys theta tau inst_loc) + +newMethodAtLoc :: InstLoc + -> Id -> [TcType] + -> NF_TcM (Inst, TcId) +newMethodAtLoc inst_loc real_id tys + -- This actually builds the Inst + = -- Get the Id type and instantiate it at the specified types + let + (tyvars,rho) = tcSplitForAllTys (idType real_id) + rho_ty = ASSERT( equalLength tyvars tys ) + substTy (mkTopTyVarSubst tyvars tys) rho + (theta, tau) = tcSplitPhiTy rho_ty + in + newMethodWith inst_loc real_id tys theta tau `thenNF_Tc` \ meth_inst -> + returnNF_Tc (meth_inst, instToId meth_inst) \end{code} -\begin{pseudocode} -mkInstSpecEnv :: Class -- class - -> Type -- instance type - -> [TyVarTemplate] -- instance tyvars - -> ThetaType -- superclasses dicts - -> SpecEnv -- specenv for dfun of instance - -mkInstSpecEnv clas inst_ty inst_tvs inst_theta - = mkSpecEnv (catMaybes (map maybe_spec_info matches)) - where - matches = matchMEnv matchTy (getClassInstEnv clas) inst_ty - - maybe_spec_info (_, match_info, MkInstTemplate dfun _ []) - = Just (SpecInfo (map (assocMaybe match_info) inst_tvs) (length inst_theta) dfun) - maybe_spec_info (_, match_info, _) - = Nothing -\end{pseudocode} - +In newOverloadedLit we convert directly to an Int or Integer if we +know that's what we want. This may save some time, by not +temporarily generating overloaded literals, but it won't catch all +cases (the rest are caught in lookupInst). \begin{code} -addClassInst - :: ClassInstEnv -- Incoming envt - -> Type -- The instance type: inst_ty - -> Id -- Dict fun id to apply. Free tyvars of inst_ty must - -- be the same as the forall'd tyvars of the dfun id. - -> MaybeErr - ClassInstEnv -- Success - (Type, Id) -- Offending overlap - -addClassInst inst_env inst_ty dfun_id = insertMEnv matchTy inst_env inst_ty dfun_id +newOverloadedLit :: InstOrigin + -> HsOverLit + -> TcType + -> NF_TcM (TcExpr, LIE) +newOverloadedLit orig lit expected_ty + | Just expr <- shortCutLit lit expected_ty + = returnNF_Tc (expr, emptyLIE) + + | otherwise + = tcGetInstLoc orig `thenNF_Tc` \ loc -> + tcGetUnique `thenNF_Tc` \ new_uniq -> + zapToType expected_ty `thenNF_Tc_` + -- 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 + in + returnNF_Tc (HsVar (instToId lit_inst), unitLIE lit_inst) + +shortCutLit :: HsOverLit -> TcType -> Maybe TcExpr +shortCutLit (HsIntegral i fi) ty + | isIntTy ty && inIntRange i && fi == fromIntegerName -- Short cut for Int + = Just (HsLit (HsInt i)) + | isIntegerTy ty && fi == fromIntegerName -- Short cut for Integer + = Just (HsLit (HsInteger i)) + +shortCutLit (HsFractional f fr) ty + | isFloatTy ty && fr == fromRationalName + = Just (mkHsConApp floatDataCon [] [HsLit (HsFloatPrim f)]) + | isDoubleTy ty && fr == fromRationalName + = Just (mkHsConApp doubleDataCon [] [HsLit (HsDoublePrim f)]) + +shortCutLit lit ty + = Nothing \end{code} - %************************************************************************ %* * -\subsection[Inst-origin]{The @InstOrigin@ type} +\subsection{Zonking} %* * %************************************************************************ -The @InstOrigin@ type gives information about where a dictionary came from. -This is important for decent error message reporting because dictionaries -don't appear in the original source code. Doubtless this type will evolve... +Zonking makes sure that the instance types are fully zonked, +but doesn't do the same for any of the Ids in an Inst. There's no +need, and it's a lot of extra work. \begin{code} -data InstOrigin s - = OccurrenceOf (TcIdOcc s) -- Occurrence of an overloaded identifier - | OccurrenceOfCon Id -- Occurrence of a data constructor +zonkInst :: Inst -> NF_TcM Inst +zonkInst (Dict id pred loc) + = zonkTcPredType pred `thenNF_Tc` \ new_pred -> + returnNF_Tc (Dict id new_pred loc) + +zonkInst (Method m id tys theta tau loc) + = zonkId id `thenNF_Tc` \ new_id -> + -- Essential to zonk the id in case it's a local variable + -- Can't use zonkIdOcc because the id might itself be + -- an InstId, in which case it won't be in scope + + zonkTcTypes tys `thenNF_Tc` \ new_tys -> + zonkTcThetaType theta `thenNF_Tc` \ new_theta -> + zonkTcType tau `thenNF_Tc` \ new_tau -> + returnNF_Tc (Method m new_id new_tys new_theta new_tau loc) + +zonkInst (LitInst id lit ty loc) + = zonkTcType ty `thenNF_Tc` \ new_ty -> + returnNF_Tc (LitInst id lit new_ty loc) - | RecordUpdOrigin +zonkInsts insts = mapNF_Tc zonkInst insts +\end{code} - | DataDeclOrigin -- Typechecking a data declaration - | InstanceDeclOrigin -- Typechecking an instance decl +%************************************************************************ +%* * +\subsection{Printing} +%* * +%************************************************************************ - | LiteralOrigin HsLit -- Occurrence of a literal +ToDo: improve these pretty-printing things. The ``origin'' is really only +relevant in error messages. - | ArithSeqOrigin RenamedArithSeqInfo -- [x..], [x..y] etc +\begin{code} +instance Outputable Inst where + ppr inst = pprInst inst + +pprInst (LitInst u lit ty loc) + = hsep [ppr lit, ptext SLIT("at"), ppr ty, show_uniq u] + +pprInst (Dict u pred loc) = pprPred pred <+> show_uniq u + +pprInst m@(Method u id tys theta tau loc) + = hsep [ppr id, ptext SLIT("at"), + brackets (sep (map pprParendType tys)) {- , + ptext SLIT("theta"), ppr theta, + ptext SLIT("tau"), ppr tau + show_uniq u, + ppr (instToId m) -}] + +show_uniq u = ifPprDebug (text "{-" <> ppr u <> text "-}") + +tidyInst :: TidyEnv -> Inst -> Inst +tidyInst env (LitInst u lit ty loc) = LitInst u lit (tidyType env ty) loc +tidyInst env (Dict u pred loc) = Dict u (tidyPred env pred) loc +tidyInst env (Method u id tys theta tau loc) = Method u id (tidyTypes env tys) theta tau loc + +tidyMoreInsts :: TidyEnv -> [Inst] -> (TidyEnv, [Inst]) +-- This function doesn't assume that the tyvars are in scope +-- so it works like tidyOpenType, returning a TidyEnv +tidyMoreInsts env insts + = (env', map (tidyInst env') insts) + where + env' = tidyFreeTyVars env (tyVarsOfInsts insts) - | SignatureOrigin -- A dict created from a type signature +tidyInsts :: [Inst] -> (TidyEnv, [Inst]) +tidyInsts insts = tidyMoreInsts emptyTidyEnv insts +\end{code} - | DoOrigin -- The monad for a do expression - | ClassDeclOrigin -- Manufactured during a class decl +%************************************************************************ +%* * +\subsection{Looking up Insts} +%* * +%************************************************************************ - | DerivingOrigin InstanceMapper - Class - TyCon +\begin{code} +data LookupInstResult s + = NoInstance + | SimpleInst TcExpr -- Just a variable, type application, or literal + | GenInst [Inst] TcExpr -- The expression and its needed insts - -- During "deriving" operations we have an ever changing - -- mapping of classes to instances, so we record it inside the - -- origin information. This is a bit of a hack, but it works - -- fine. (Simon is to blame [WDP].) +lookupInst :: Inst + -> NF_TcM (LookupInstResult s) - | InstanceSpecOrigin InstanceMapper - Class -- in a SPECIALIZE instance pragma - Type +-- Dictionaries - -- When specialising instances the instance info attached to - -- each class is not yet ready, so we record it inside the - -- origin information. This is a bit of a hack, but it works - -- fine. (Patrick is to blame [WDP].) +lookupInst dict@(Dict _ (ClassP clas tys) loc) + = getDOptsTc `thenNF_Tc` \ dflags -> + tcGetInstEnv `thenNF_Tc` \ 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. + let + (tyvars, rho) = tcSplitForAllTys (idType dfun_id) + mk_ty_arg tv = case lookupSubstEnv tenv tv of + Just (DoneTy ty) -> returnNF_Tc ty + Nothing -> tcInstTyVar VanillaTv tv `thenNF_Tc` \ tc_tv -> + returnTc (mkTyVarTy tc_tv) + in + mapNF_Tc mk_ty_arg tyvars `thenNF_Tc` \ 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 + returnNF_Tc (SimpleInst ty_app) + else + newDictsAtLoc loc theta `thenNF_Tc` \ dicts -> + let + rhs = mkHsDictApp ty_app (map instToId dicts) + in + returnNF_Tc (GenInst dicts rhs) - | DefaultDeclOrigin -- Related to a `default' declaration + other -> returnNF_Tc NoInstance - | ValSpecOrigin Name -- in a SPECIALIZE pragma for a value +lookupInst dict@(Dict _ _ loc) = returnNF_Tc NoInstance - -- Argument or result of a ccall - -- Dictionaries with this origin aren't actually mentioned in the - -- translated term, and so need not be bound. Nor should they - -- be abstracted over. +-- Methods - | CCallOrigin String -- CCall label - (Maybe RenamedHsExpr) -- Nothing if it's the result - -- Just arg, for an argument +lookupInst inst@(Method _ id tys theta _ loc) + = newDictsAtLoc loc theta `thenNF_Tc` \ dicts -> + returnNF_Tc (GenInst dicts (mkHsDictApp (mkHsTyApp (HsVar id) tys) (map instToId dicts))) - | LitLitOrigin String -- the litlit +-- Literals - | UnknownOrigin -- Help! I give up... +-- Look for short cuts first: if the literal is *definitely* a +-- int, integer, float or a double, generate the real thing here. +-- This is essential (see nofib/spectral/nucleic). +-- [Same shortcut as in newOverloadedLit, but we +-- may have done some unification by now] + +lookupInst inst@(LitInst u lit ty loc) + | Just expr <- shortCutLit lit ty + = returnNF_Tc (GenInst [] expr) -- GenInst, not SimpleInst, because + -- expr may be a constructor application + +lookupInst inst@(LitInst u (HsIntegral i from_integer_name) ty loc) + = tcLookupId from_integer_name `thenNF_Tc` \ from_integer -> + newMethodAtLoc loc from_integer [ty] `thenNF_Tc` \ (method_inst, method_id) -> + returnNF_Tc (GenInst [method_inst] + (HsApp (HsVar method_id) (HsLit (HsInteger i)))) + + +lookupInst inst@(LitInst u (HsFractional f from_rat_name) ty loc) + = tcLookupId from_rat_name `thenNF_Tc` \ from_rational -> + newMethodAtLoc loc from_rational [ty] `thenNF_Tc` \ (method_inst, method_id) -> + let + rational_ty = tcFunArgTy (idType method_id) + rational_lit = HsLit (HsRat f rational_ty) + in + returnNF_Tc (GenInst [method_inst] (HsApp (HsVar method_id) rational_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} --- During deriving and instance specialisation operations --- we can't get the instances of the class from inside the --- class, because the latter ain't ready yet. Instead we --- find a mapping from classes to envts inside the dict origin. - -get_inst_env :: Class -> InstOrigin s -> ClassInstEnv -get_inst_env clas (DerivingOrigin inst_mapper _ _) - = fst (inst_mapper clas) -get_inst_env clas (InstanceSpecOrigin inst_mapper _ _) - = fst (inst_mapper clas) -get_inst_env clas other_orig = getClassInstEnv clas - - -pprOrigin :: PprStyle -> InstOrigin s -> Pretty - -pprOrigin sty (OccurrenceOf id) - = ppBesides [ppPStr SLIT("at a use of an overloaded identifier: `"), - ppr sty id, ppChar '\''] -pprOrigin sty (OccurrenceOfCon id) - = ppBesides [ppPStr SLIT("at a use of an overloaded constructor: `"), - ppr sty id, ppChar '\''] -pprOrigin sty (InstanceDeclOrigin) - = ppStr "in an instance declaration" -pprOrigin sty (LiteralOrigin lit) - = ppCat [ppStr "at an overloaded literal:", ppr sty lit] -pprOrigin sty (ArithSeqOrigin seq) - = ppCat [ppStr "at an arithmetic sequence:", ppr sty seq] -pprOrigin sty (SignatureOrigin) - = ppStr "in a type signature" -pprOrigin sty (DoOrigin) - = ppStr "in a do statement" -pprOrigin sty (ClassDeclOrigin) - = ppStr "in a class declaration" -pprOrigin sty (DerivingOrigin _ clas tycon) - = ppBesides [ppStr "in a `deriving' clause; class `", - ppr sty clas, - ppStr "'; offending type `", - ppr sty tycon, - ppStr "'"] -pprOrigin sty (InstanceSpecOrigin _ clas ty) - = ppBesides [ppStr "in a SPECIALIZE instance pragma; class \"", - ppr sty clas, ppStr "\" type: ", ppr sty ty] -pprOrigin sty (DefaultDeclOrigin) - = ppStr "in a `default' declaration" -pprOrigin sty (ValSpecOrigin name) - = ppBesides [ppStr "in a SPECIALIZE user-pragma for `", - ppr sty name, ppStr "'"] -pprOrigin sty (CCallOrigin clabel Nothing{-ccall result-}) - = ppBesides [ppStr "in the result of the _ccall_ to `", - ppStr clabel, ppStr "'"] -pprOrigin sty (CCallOrigin clabel (Just arg_expr)) - = ppBesides [ppStr "in an argument in the _ccall_ to `", - ppStr clabel, ppStr "', namely: ", ppr sty arg_expr] -pprOrigin sty (LitLitOrigin s) - = ppBesides [ppStr "in this ``literal-literal'': ", ppStr s] -pprOrigin sty UnknownOrigin - = ppStr "in... oops -- I don't know where the overloading came from!" +lookupSimpleInst :: Class + -> [Type] -- Look up (c,t) + -> NF_TcM (Maybe ThetaType) -- Here are the needed (c,t)s + +lookupSimpleInst clas tys + = getDOptsTc `thenNF_Tc` \ dflags -> + tcGetInstEnv `thenNF_Tc` \ inst_env -> + case lookupInstEnv dflags inst_env clas tys of + FoundInst tenv dfun + -> returnNF_Tc (Just (substTheta (mkSubst emptyInScopeSet tenv) theta)) + where + (_, rho) = tcSplitForAllTys (idType dfun) + (theta,_) = tcSplitPhiTy rho + + other -> returnNF_Tc Nothing \end{code} - - -