X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FInst.lhs;h=9f3c6842c5ff65917b0ba746b11f06ca8c28a877;hb=8655d6ca41df4aa77a559d4067ad3815797b9803;hp=3cdbf52f29eb419a58d4cbf23e8c92916efbffa0;hpb=b4775e5e760111e2d71fba3c44882dce390edfb2;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/Inst.lhs b/ghc/compiler/typecheck/Inst.lhs index 3cdbf52..9f3c684 100644 --- a/ghc/compiler/typecheck/Inst.lhs +++ b/ghc/compiler/typecheck/Inst.lhs @@ -5,192 +5,81 @@ \begin{code} module Inst ( - LIE, emptyLIE, unitLIE, plusLIE, consLIE, zonkLIE, + LIE, emptyLIE, unitLIE, plusLIE, consLIE, plusLIEs, mkLIE, isEmptyLIE, lieToList, listToLIE, + showLIE, Inst, - pprInst, pprInsts, pprInstsInFull, tidyInsts, + pprInst, pprInsts, pprInstsInFull, tidyInsts, tidyMoreInsts, - newDictsFromOld, newDicts, - newMethod, newMethodWithGivenTy, newOverloadedLit, - newIPDict, tcInstId, + newDictsFromOld, newDicts, cloneDict, + newOverloadedLit, newIPDict, + newMethod, newMethodFromName, newMethodWithGivenTy, + tcInstClassOp, tcInstCall, tcInstDataCon, + tcSyntaxName, tcStdSyntaxName, - tyVarsOfInst, tyVarsOfInsts, tyVarsOfLIE, instLoc, getDictClassTys, - getIPs, - predsOfInsts, predsOfInst, + tyVarsOfInst, tyVarsOfInsts, tyVarsOfLIE, + ipNamesOfInst, ipNamesOfInsts, fdPredsOfInst, fdPredsOfInsts, + instLoc, getDictClassTys, dictPred, - lookupInst, lookupSimpleInst, LookupInstResult(..), + lookupInst, LookupInstResult(..), - isDict, isClassDict, isMethod, instMentionsIPs, + isDict, isClassDict, isMethod, + isLinearInst, linearInstType, isIPDict, isInheritableInst, isTyVarDict, isStdClassTyVarDict, isMethodFor, instBindingRequired, instCanBeGeneralised, zonkInst, zonkInsts, instToId, instName, - InstOrigin(..), InstLoc, pprInstLoc + InstOrigin(..), InstLoc(..), pprInstLoc ) where #include "HsVersions.h" -import CmdLineOpts ( opt_NoMethodSharing ) +import {-# SOURCE #-} TcExpr( tcCheckSigma ) + import HsSyn ( HsLit(..), HsOverLit(..), HsExpr(..) ) -import TcHsSyn ( TcExpr, TcId, - mkHsTyApp, mkHsDictApp, mkHsConApp, zonkId +import TcHsSyn ( TcExpr, TcId, TcIdSet, + mkHsTyApp, mkHsDictApp, mkHsConApp, zonkId, + mkCoercion, ExprCoFn ) -import TcMonad -import TcEnv ( TcIdSet, tcGetInstEnv, tcLookupSyntaxId ) +import TcRnMonad +import TcEnv ( tcGetInstEnv, tcLookupId, tcLookupTyCon, checkWellStaged, topIdLvl ) import InstEnv ( InstLookupResult(..), lookupInstEnv ) -import TcType ( TcThetaType, - TcType, TcTauType, TcTyVarSet, - zonkTcType, zonkTcTypes, zonkTcPredType, - zonkTcThetaType, tcInstTyVar, tcInstType +import TcMType ( zonkTcType, zonkTcTypes, zonkTcPredType, + zonkTcThetaType, tcInstTyVar, tcInstType, tcInstTyVars ) -import CoreFVs ( idFreeTyVars ) -import Class ( Class ) -import Id ( Id, idName, idType, mkUserLocal, mkSysLocal, mkLocalId ) -import PrelInfo ( isStandardClass, isCcallishClass, isNoDictClass ) -import Name ( Name, mkMethodOcc, getOccName ) -import NameSet ( NameSet ) -import PprType ( pprPred ) -import Type ( Type, PredType(..), ThetaType, - isTyVarTy, mkPredTy, mkTyVarTy, mkTyVarTys, - splitForAllTys, splitSigmaTy, funArgTy, - splitMethodTy, splitRhoTy, +import TcType ( Type, TcType, TcThetaType, TcTyVarSet, + SourceType(..), PredType, TyVarDetails(VanillaTv), + tcSplitForAllTys, tcSplitForAllTys, mkTyConApp, + tcSplitPhiTy, mkGenTyConApp, + isIntTy,isFloatTy, isIntegerTy, isDoubleTy, + tcIsTyVarTy, mkPredTy, mkTyVarTy, mkTyVarTys, tyVarsOfType, tyVarsOfTypes, tyVarsOfPred, tidyPred, - predMentionsIPs, isClassPred, isTyVarClassPred, + isClassPred, isTyVarClassPred, isLinearPred, getClassPredTys, getClassPredTys_maybe, mkPredName, - tidyType, tidyTypes, tidyFreeTyVars - ) -import Subst ( emptyInScopeSet, mkSubst, - substTy, substTheta, mkTyVarSubst, mkTopTyVarSubst + isInheritablePred, isIPPred, + tidyType, tidyTypes, tidyFreeTyVars, tcSplitSigmaTy ) +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 Subst ( substTy, substTyWith, substTheta, mkTyVarSubst ) import Literal ( inIntRange ) -import VarEnv ( TidyEnv, lookupSubstEnv, SubstResult(..) ) +import Var ( TyVar ) +import VarEnv ( TidyEnv, emptyTidyEnv, lookupSubstEnv, SubstResult(..) ) import VarSet ( elemVarSet, emptyVarSet, unionVarSet ) -import TysWiredIn ( isIntTy, - floatDataCon, isFloatTy, - doubleDataCon, isDoubleTy, - isIntegerTy - ) -import PrelNames( fromIntegerName, fromRationalName ) -import Util ( thenCmp ) -import Bag +import TysWiredIn ( floatDataCon, doubleDataCon ) +import PrelNames( fromIntegerName, fromRationalName, rationalTyConName ) +import BasicTypes( IPName(..), mapIPName, ipNameName ) +import UniqSupply( uniqsFromSupply ) import Outputable \end{code} -%************************************************************************ -%* * -\subsection[Inst-collections]{LIE: a collection of Insts} -%* * -%************************************************************************ - -\begin{code} -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 -> 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} - -%************************************************************************ -%* * -\subsection[Inst-types]{@Inst@ types} -%* * -%************************************************************************ - -An @Inst@ is either a dictionary, an instance of an overloaded -literal, or an instance of an overloaded value. We call the latter a -``method'' even though it may not correspond to a class operation. -For example, we might have an instance of the @double@ function at -type Int, represented by - - Method 34 doubleId [Int] origin - -\begin{code} -data Inst - = Dict - Id - TcPredType - InstLoc - - | Method - Id - - 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] -- The types to which its polymorphic tyvars - -- should be instantiated. - -- These types must saturate the Id's foralls. - - TcThetaType -- The (types of the) dictionaries to which the function - -- must be applied to get the method - - TcTauType -- The type of the method - - InstLoc - - -- INVARIANT: in (Method u f tys theta tau loc) - -- type of (f tys dicts(from theta)) = tau - - | 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} -instance Ord Inst where - compare = cmpInst - -instance Eq Inst where - (==) i1 i2 = case i1 `cmpInst` i2 of - EQ -> True - other -> False - -cmpInst (Dict _ pred1 _) (Dict _ pred2 _) = (pred1 `compare` pred2) -cmpInst (Dict _ _ _) other = LT - -cmpInst (Method _ _ _ _ _ _) (Dict _ _ _) = GT -cmpInst (Method _ id1 tys1 _ _ _) (Method _ id2 tys2 _ _ _) = (id1 `compare` id2) `thenCmp` (tys1 `compare` tys2) -cmpInst (Method _ _ _ _ _ _) other = LT - -cmpInst (LitInst _ lit1 ty1 _) (LitInst _ lit2 ty2 _) = (lit1 `compare` lit2) `thenCmp` (ty1 `compare` ty2) -cmpInst (LitInst _ _ _ _) other = GT - --- and they can only have HsInt or HsFracs in them. -\end{code} - Selection ~~~~~~~~~ @@ -207,22 +96,38 @@ 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 +-- fdPredsOfInst is used to get predicates that contain functional +-- 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 + +isInheritableInst (Dict _ pred _) = isInheritablePred pred +isInheritableInst (Method _ _ _ theta _ _) = all isInheritablePred theta +isInheritableInst other = True -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. -ipsOfPreds theta = [(n,ty) | IParam n ty <- theta] +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] -getIPs inst = ipsOfPreds (predsOfInst 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 @@ -231,6 +136,7 @@ tyVarsOfInst (Method _ id tys _ _ _) = tyVarsOfTypes tys `unionVarSet` idFreeTyV -- 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} @@ -250,6 +156,10 @@ isTyVarDict :: Inst -> Bool isTyVarDict (Dict _ pred _) = isTyVarClassPred pred isTyVarDict other = False +isIPDict :: Inst -> Bool +isIPDict (Dict _ pred _) = isIPPred pred +isIPDict other = False + isMethod :: Inst -> Bool isMethod (Method _ _ _ _ _ _) = True isMethod other = False @@ -258,15 +168,20 @@ isMethodFor :: TcIdSet -> Inst -> Bool isMethodFor ids (Method uniq id tys _ _ loc) = id `elemVarSet` ids isMethodFor ids inst = False -instMentionsIPs :: Inst -> NameSet -> Bool - -- True if the Inst mentions any of the implicit - -- parameters in the supplied set of names -instMentionsIPs (Dict _ pred _) ip_names = pred `predMentionsIPs` ip_names -instMentionsIPs (Method _ _ _ theta _ _) ip_names = any (`predMentionsIPs` ip_names) theta -instMentionsIPs other ip_names = 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 + +linearInstType :: Inst -> TcType -- %x::t --> t +linearInstType (Dict _ (IParam _ ty) _) = ty + isStdClassTyVarDict (Dict _ pred _) = case getClassPredTys_maybe pred of - Just (clas, [ty]) -> isStandardClass clas && isTyVarTy ty + Just (clas, [ty]) -> isStandardClass clas && tcIsTyVarTy ty other -> False \end{code} @@ -278,7 +193,6 @@ must be witnessed by an actual binding; the second tells whether an \begin{code} instBindingRequired :: Inst -> Bool instBindingRequired (Dict _ (ClassP clas _) _) = not (isNoDictClass clas) -instBindingRequired (Dict _ (IParam _ _) _) = False instBindingRequired other = True instCanBeGeneralised :: Inst -> Bool @@ -296,134 +210,141 @@ instCanBeGeneralised other = True \begin{code} newDicts :: InstOrigin -> TcThetaType - -> NF_TcM [Inst] + -> TcM [Inst] newDicts orig theta - = tcGetInstLoc orig `thenNF_Tc` \ loc -> + = getInstLoc orig `thenM` \ loc -> newDictsAtLoc loc theta -newDictsFromOld :: Inst -> TcThetaType -> NF_TcM [Inst] +cloneDict :: Inst -> TcM Inst +cloneDict (Dict id ty loc) = newUnique `thenM` \ uniq -> + returnM (Dict (setIdUnique id uniq) ty loc) + +newDictsFromOld :: Inst -> TcThetaType -> 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) + -> TcM [Inst] +newDictsAtLoc inst_loc theta + = newUniqueSupply `thenM` \ us -> + returnM (zipWith mk_dict (uniqsFromSupply us) theta) where - mk_dict uniq pred = Dict (mkLocalId (mkPredName uniq loc pred) (mkPredTy pred)) pred inst_loc - --- For implicit parameters, since there is only one in scope --- at any time, we use the name of the implicit parameter itself -newIPDict orig name ty - = tcGetInstLoc orig `thenNF_Tc` \ inst_loc -> - returnNF_Tc (Dict (mkLocalId name (mkPredTy pred)) pred inst_loc) - where pred = IParam name ty + mk_dict uniq pred = Dict (mkLocalId (mkPredName uniq loc pred) (mkPredTy pred)) + pred inst_loc + loc = instLocSrcLoc 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 + -> TcM (IPName Id, Inst) +newIPDict orig ip_name ty + = getInstLoc orig `thenM` \ inst_loc@(InstLoc _ loc _) -> + newUnique `thenM` \ uniq -> + let + pred = IParam ip_name ty + id = mkLocalId (mkPredName uniq loc pred) (mkPredTy pred) + in + returnM (mapIPName (\n -> id) ip_name, Dict id pred inst_loc) \end{code} + %************************************************************************ %* * \subsection{Building methods (calls of overloaded functions)} %* * %************************************************************************ -tcInstId instantiates an occurrence of an Id. -The instantiate_it loop runs round instantiating the Id. -It has to be a loop because we are now prepared to entertain -types like - f:: forall a. Eq a => forall b. Baz b => tau -We want to instantiate this to - f2::tau {f2 = f1 b (Baz b), f1 = f a (Eq a)} - -The -fno-method-sharing flag controls what happens so far as the LIE -is concerned. The default case is that for an overloaded function we -generate a "method" Id, and add the Method Inst to the LIE. So you get -something like - f :: Num a => a -> a - f = /\a (d:Num a) -> let m = (+) a d in \ (x:a) -> m x x -If you specify -fno-method-sharing, the dictionary application -isn't shared, so we get - f :: Num a => a -> a - f = /\a (d:Num a) (x:a) -> (+) a d x x -This gets a bit less sharing, but - a) it's better for RULEs involving overloaded functions - b) perhaps fewer separated lambdas - \begin{code} -tcInstId :: Id -> NF_TcM (TcExpr, LIE, TcType) -tcInstId fun - | opt_NoMethodSharing = loop_noshare (HsVar fun) (idType fun) - | otherwise = loop_share fun - where - orig = OccurrenceOf fun - loop_noshare fun fun_ty - = tcInstType fun_ty `thenNF_Tc` \ (tyvars, theta, tau) -> - let - ty_app = mkHsTyApp fun (mkTyVarTys tyvars) - in - if null theta then -- Is it overloaded? - returnNF_Tc (ty_app, emptyLIE, tau) - else - newDicts orig theta `thenNF_Tc` \ dicts -> - loop_noshare (mkHsDictApp ty_app (map instToId dicts)) tau `thenNF_Tc` \ (expr, lie, final_tau) -> - returnNF_Tc (expr, mkLIE dicts `plusLIE` lie, final_tau) - - loop_share fun - = tcInstType (idType fun) `thenNF_Tc` \ (tyvars, theta, tau) -> - let - arg_tys = mkTyVarTys tyvars - in - if null theta then -- Is it overloaded? - returnNF_Tc (mkHsTyApp (HsVar fun) arg_tys, emptyLIE, tau) - else - -- Yes, it's overloaded - newMethodWithGivenTy orig fun arg_tys theta tau `thenNF_Tc` \ meth -> - loop_share (instToId meth) `thenNF_Tc` \ (expr, lie, final_tau) -> - returnNF_Tc (expr, unitLIE meth `plusLIE` lie, final_tau) - - -newMethod :: InstOrigin - -> TcId - -> [TcType] - -> NF_TcM Inst -newMethod orig id tys - = -- Get the Id type and instantiate it at the specified types +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 -> + extendLIEs dicts `thenM_` let - (tyvars, rho) = splitForAllTys (idType id) - rho_ty = substTy (mkTyVarSubst tyvars tys) rho - (pred, tau) = splitMethodTy rho_ty + inst_fn e = mkHsDictApp (mkHsTyApp e (mkTyVarTys tyvars)) (map instToId dicts) + in + returnM (mkCoercion inst_fn, tau) + +tcInstDataCon :: InstOrigin -> DataCon + -> TcM ([TcType], -- Types to instantiate at + [Inst], -- Existential dictionaries to apply to + [TcType], -- Argument types of constructor + TcType, -- Result type + [TyVar]) -- Existential tyvars +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 - newMethodWithGivenTy orig id tys [pred] tau + tcInstTyVars VanillaTv (tvs ++ ex_tvs) `thenM` \ (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' `thenM` \ stupid_dicts -> + newDicts orig ex_theta' `thenM` \ ex_dicts -> + + -- Note that we return the stupid theta *only* in the LIE; + -- we don't otherwise use it at all + extendLIEs stupid_dicts `thenM_` + + returnM (ty_args', ex_dicts, arg_tys', result_ty, ex_tvs') + +newMethodFromName :: InstOrigin -> TcType -> Name -> TcM TcId +newMethodFromName origin ty name + = tcLookupId name `thenM` \ 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. + getInstLoc origin `thenM` \ loc -> + tcInstClassOp loc id [ty] `thenM` \ inst -> + extendLIE inst `thenM_` + returnM (instToId inst) newMethodWithGivenTy orig id tys theta tau - = tcGetInstLoc orig `thenNF_Tc` \ loc -> - newMethodWith loc id tys theta tau + = getInstLoc orig `thenM` \ loc -> + newMethod loc id tys theta tau `thenM` \ inst -> + extendLIE inst `thenM_` + returnM (instToId inst) + +-------------------------------------------- +-- tcInstClassOp, and newMethod do *not* drop the +-- Inst into the LIE; they just returns the Inst +-- This is important because they are used by TcSimplify +-- to simplify Insts + +tcInstClassOp :: InstLoc -> Id -> [TcType] -> TcM Inst +tcInstClassOp inst_loc sel_id tys + = let + (tyvars,rho) = tcSplitForAllTys (idType sel_id) + rho_ty = ASSERT( length tyvars == length tys ) + substTyWith tyvars tys rho + (preds,tau) = tcSplitPhiTy rho_ty + in + newMethod inst_loc sel_id tys preds tau -newMethodWith inst_loc@(_,loc,_) id tys theta tau - = tcGetUnique `thenNF_Tc` \ new_uniq -> +--------------------------- +newMethod inst_loc id tys theta tau + = newUnique `thenM` \ new_uniq -> let meth_id = mkUserLocal (mkMethodOcc (getOccName id)) new_uniq tau loc + inst = Method meth_id id tys theta tau inst_loc + loc = instLocSrcLoc inst_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) = splitForAllTys (idType real_id) - rho_ty = ASSERT( length tyvars == length tys ) - substTy (mkTopTyVarSubst tyvars tys) rho - (theta, tau) = splitRhoTy rho_ty - in - newMethodWith inst_loc real_id tys theta tau `thenNF_Tc` \ meth_inst -> - returnNF_Tc (meth_inst, instToId meth_inst) + returnM inst \end{code} In newOverloadedLit we convert directly to an Int or Integer if we @@ -435,26 +356,65 @@ cases (the rest are caught in lookupInst). newOverloadedLit :: InstOrigin -> HsOverLit -> TcType - -> NF_TcM (TcExpr, LIE) -newOverloadedLit orig (HsIntegral i) ty - | isIntTy ty && inIntRange i -- Short cut for Int - = returnNF_Tc (int_lit, emptyLIE) - - | isIntegerTy ty -- Short cut for Integer - = returnNF_Tc (integer_lit, emptyLIE) - - where - int_lit = HsLit (HsInt i) - integer_lit = HsLit (HsInteger i) - -newOverloadedLit orig lit ty -- The general case - = tcGetInstLoc orig `thenNF_Tc` \ loc -> - tcGetUnique `thenNF_Tc` \ new_uniq -> + -> TcM TcExpr +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, HsVar fi) `thenM` \ (_,expr) -> + returnM (HsApp expr (HsLit (HsInteger i))) + + | Just expr <- shortCutIntLit i expected_ty + = returnM expr + + | otherwise + = newLitInst orig lit expected_ty + +newOverloadedLit orig lit@(HsFractional r fr) expected_ty + | fr /= fromRationalName -- c.f. HsIntegral case + = 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 + = returnM expr + + | otherwise + = newLitInst orig lit expected_ty + +newLitInst orig lit expected_ty + = getInstLoc orig `thenM` \ loc -> + newUnique `thenM` \ new_uniq -> + let + lit_inst = LitInst lit_id lit expected_ty loc + lit_id = mkSysLocal FSLIT("lit") new_uniq expected_ty + in + extendLIE lit_inst `thenM_` + returnM (HsVar (instToId lit_inst)) + +shortCutIntLit :: Integer -> TcType -> Maybe TcExpr +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)) + | otherwise = Nothing + +shortCutFracLit :: Rational -> TcType -> Maybe TcExpr +shortCutFracLit f ty + | isFloatTy ty + = Just (mkHsConApp floatDataCon [] [HsLit (HsFloatPrim f)]) + | isDoubleTy ty + = Just (mkHsConApp doubleDataCon [] [HsLit (HsDoublePrim f)]) + | otherwise = Nothing + +mkRatLit :: Rational -> TcM TcExpr +mkRatLit r + = tcLookupTyCon rationalTyConName `thenM` \ rat_tc -> let - lit_inst = LitInst lit_id lit ty loc - lit_id = mkSysLocal SLIT("lit") new_uniq ty + rational_ty = mkGenTyConApp rat_tc [] in - returnNF_Tc (HsVar (instToId lit_inst), unitLIE lit_inst) + returnM (HsLit (HsRat r rational_ty)) \end{code} @@ -469,27 +429,27 @@ 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} -zonkInst :: Inst -> NF_TcM Inst +zonkInst :: Inst -> TcM Inst zonkInst (Dict id pred loc) - = zonkTcPredType pred `thenNF_Tc` \ new_pred -> - returnNF_Tc (Dict id new_pred loc) + = zonkTcPredType pred `thenM` \ new_pred -> + returnM (Dict id new_pred loc) zonkInst (Method m id tys theta tau loc) - = zonkId id `thenNF_Tc` \ new_id -> + = zonkId id `thenM` \ 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) + zonkTcTypes tys `thenM` \ new_tys -> + zonkTcThetaType theta `thenM` \ new_theta -> + zonkTcType tau `thenM` \ new_tau -> + returnM (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) + = zonkTcType ty `thenM` \ new_ty -> + returnM (LitInst id lit new_ty loc) -zonkInsts insts = mapNF_Tc zonkInst insts +zonkInsts insts = mappM zonkInst insts \end{code} @@ -506,6 +466,14 @@ relevant in error messages. instance Outputable Inst where ppr inst = pprInst inst +pprInsts :: [Inst] -> SDoc +pprInsts insts = parens (sep (punctuate comma (map pprInst insts))) + +pprInstsInFull insts + = vcat (map go insts) + where + 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] @@ -513,7 +481,7 @@ 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 (interppSP tys) {- , + brackets (sep (map pprParendType tys)) {- , ptext SLIT("theta"), ppr theta, ptext SLIT("tau"), ppr tau show_uniq u, @@ -526,13 +494,22 @@ 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 -tidyInsts :: [Inst] -> (TidyEnv, [Inst]) +tidyMoreInsts :: TidyEnv -> [Inst] -> (TidyEnv, [Inst]) -- This function doesn't assume that the tyvars are in scope -- so it works like tidyOpenType, returning a TidyEnv -tidyInsts insts - = (env, map (tidyInst env) insts) +tidyMoreInsts env insts + = (env', map (tidyInst env') insts) where - env = tidyFreeTyVars emptyTidyEnv (tyVarsOfInsts insts) + env' = tidyFreeTyVars env (tyVarsOfInsts insts) + +tidyInsts :: [Inst] -> (TidyEnv, [Inst]) +tidyInsts insts = tidyMoreInsts emptyTidyEnv insts + +showLIE :: SDoc -> TcM () -- Debugging +showLIE str + = do { lie_var <- getLIEVar ; + lie <- readMutVar lie_var ; + traceTc (str <+> pprInstsInFull (lieToList lie)) } \end{code} @@ -548,111 +525,166 @@ data LookupInstResult s | SimpleInst TcExpr -- Just a variable, type application, or literal | GenInst [Inst] TcExpr -- The expression and its needed insts -lookupInst :: Inst - -> NF_TcM (LookupInstResult s) +lookupInst :: Inst -> TcM (LookupInstResult s) +-- It's important that lookupInst does not put any new stuff into +-- the LIE. Instead, any Insts needed by the lookup are returned in +-- the LookupInstResult, where they can be further processed by tcSimplify --- Dictionaries -lookupInst dict@(Dict _ (ClassP clas tys) loc) - = tcGetInstEnv `thenNF_Tc` \ inst_env -> - case lookupInstEnv inst_env clas tys of +-- 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 - -> let - (tyvars, rho) = splitForAllTys (idType 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) -> returnNF_Tc ty - Nothing -> tcInstTyVar tv `thenNF_Tc` \ tc_tv -> - returnTc (mkTyVarTy tc_tv) + Just (DoneTy ty) -> returnM ty + Nothing -> tcInstTyVar VanillaTv tv `thenM` \ tc_tv -> + returnM (mkTyVarTy tc_tv) in - mapNF_Tc mk_ty_arg tyvars `thenNF_Tc` \ ty_args -> + mappM mk_ty_arg tyvars `thenM` \ ty_args -> let - subst = mkTyVarSubst tyvars ty_args - dfun_rho = substTy subst rho - (theta, _) = splitRhoTy dfun_rho - ty_app = mkHsTyApp (HsVar dfun_id) ty_args + 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) + returnM (SimpleInst ty_app) else - newDictsAtLoc loc theta `thenNF_Tc` \ dicts -> + newDictsAtLoc loc theta `thenM` \ dicts -> let rhs = mkHsDictApp ty_app (map instToId dicts) in - returnNF_Tc (GenInst dicts rhs) + returnM (GenInst dicts rhs) - other -> returnNF_Tc NoInstance + other -> returnM NoInstance -lookupInst dict@(Dict _ _ loc) = returnNF_Tc NoInstance +lookupInst (Dict _ _ _) = returnM NoInstance -- Methods 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))) + = newDictsAtLoc loc theta `thenM` \ dicts -> + returnM (GenInst dicts (mkHsDictApp (mkHsTyApp (HsVar id) tys) (map instToId dicts))) -- Literals -lookupInst inst@(LitInst u (HsIntegral i) ty loc) - | isIntTy ty && in_int_range -- Short cut for Int - = returnNF_Tc (GenInst [] int_lit) - -- GenInst, not SimpleInst, because int_lit is actually a constructor application +-- 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 (HsIntegral i from_integer_name) ty loc) + | Just expr <- shortCutIntLit i ty + = returnM (GenInst [] expr) -- GenInst, not SimpleInst, because + -- expr may be a constructor application + | otherwise + = ASSERT( from_integer_name == fromIntegerName ) -- A LitInst invariant + tcLookupId fromIntegerName `thenM` \ from_integer -> + tcInstClassOp loc from_integer [ty] `thenM` \ method_inst -> + returnM (GenInst [method_inst] + (HsApp (HsVar (instToId method_inst)) (HsLit (HsInteger i)))) + + +lookupInst inst@(LitInst u (HsFractional f from_rat_name) ty loc) + | Just expr <- shortCutFracLit f ty + = returnM (GenInst [] expr) + + | otherwise + = ASSERT( from_rat_name == fromRationalName ) -- A LitInst invariant + 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)) +\end{code} - | isIntegerTy ty -- Short cut for Integer - = returnNF_Tc (GenInst [] integer_lit) - | otherwise -- Alas, it is overloaded and a big literal! - = tcLookupSyntaxId fromIntegerName `thenNF_Tc` \ from_integer -> - newMethodAtLoc loc from_integer [ty] `thenNF_Tc` \ (method_inst, method_id) -> - returnNF_Tc (GenInst [method_inst] (HsApp (HsVar method_id) integer_lit)) - where - in_int_range = inIntRange i - integer_lit = HsLit (HsInteger i) - int_lit = HsLit (HsInt i) --- similar idea for overloaded floating point literals: if the literal is --- *definitely* a float or a double, generate the real thing here. --- This is essential (see nofib/spectral/nucleic). +%************************************************************************ +%* * + Re-mappable syntax +%* * +%************************************************************************ -lookupInst inst@(LitInst u (HsFractional f) ty loc) - | isFloatTy ty = returnNF_Tc (GenInst [] float_lit) - | isDoubleTy ty = returnNF_Tc (GenInst [] double_lit) - | otherwise - = tcLookupSyntaxId fromRationalName `thenNF_Tc` \ from_rational -> - newMethodAtLoc loc from_rational [ty] `thenNF_Tc` \ (method_inst, method_id) -> - let - rational_ty = funArgTy (idType method_id) - rational_lit = HsLit (HsRat f rational_ty) - in - returnNF_Tc (GenInst [method_inst] (HsApp (HsVar method_id) rational_lit)) +Suppose we are doing the -fno-implicit-prelude thing, and we encounter +a do-expression. We have to find (>>) in the current environment, which is +done by the rename. Then we have to check that it has the same type as +Control.Monad.(>>). Or, more precisely, a compatible type. One 'customer' had +this: - where - floatprim_lit = HsLit (HsFloatPrim f) - float_lit = mkHsConApp floatDataCon [] [floatprim_lit] - doubleprim_lit = HsLit (HsDoublePrim f) - double_lit = mkHsConApp doubleDataCon [] [doubleprim_lit] -\end{code} + (>>) :: HB m n mn => m a -> n b -> mn b + +So the idea is to generate a local binding for (>>), thus: + + let then72 :: forall a b. m a -> m b -> m b + then72 = ...something involving the user's (>>)... + in + ...the do-expression... -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. +Now the do-expression can proceed using then72, which has exactly +the expected type. + +In fact tcSyntaxName just generates the RHS for then72, because we only +want an actual binding in the do-expression case. For literals, we can +just use the expression inline. \begin{code} -lookupSimpleInst :: Class - -> [Type] -- Look up (c,t) - -> NF_TcM (Maybe ThetaType) -- Here are the needed (c,t)s - -lookupSimpleInst clas tys - = tcGetInstEnv `thenNF_Tc` \ inst_env -> - case lookupInstEnv inst_env clas tys of - FoundInst tenv dfun - -> returnNF_Tc (Just (substTheta (mkSubst emptyInScopeSet tenv) theta)) - where - (_, theta, _) = splitSigmaTy (idType dfun) - - other -> returnNF_Tc Nothing -\end{code} +tcSyntaxName :: InstOrigin + -> TcType -- Type to instantiate it at + -> (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, HsVar user_nm) + | std_nm == user_nm + = tcStdSyntaxName orig ty std_nm + +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_expr orig tau1) $ + tcCheckSigma user_nm_expr tau1 `thenM` \ expr -> + returnM (std_nm, expr) + +tcStdSyntaxName :: InstOrigin + -> TcType -- Type to instantiate it at + -> Name -- Standard name + -> TcM (Name, TcExpr) -- (Standard name, suitable expression) +tcStdSyntaxName orig ty std_nm + = newMethodFromName orig ty std_nm `thenM` \ id -> + returnM (std_nm, HsVar id) +syntaxNameCtxt name orig ty tidy_env + = getInstLoc orig `thenM` \ inst_loc -> + let + msg = vcat [ptext SLIT("When checking that") <+> quotes (ppr name) <+> + ptext SLIT("(needed by a syntactic construct)"), + nest 2 (ptext SLIT("has the required type:") <+> ppr (tidyType tidy_env ty)), + nest 2 (pprInstLoc inst_loc)] + in + returnM (tidy_env, msg) +\end{code}