X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FInst.lhs;h=9f3c6842c5ff65917b0ba746b11f06ca8c28a877;hb=8655d6ca41df4aa77a559d4067ad3815797b9803;hp=f7a8472e2d21cee5053f7448ceb9dc7d16fe66b7;hpb=6433e4f62f2124744ce2276c77a2c243f014d717;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/Inst.lhs b/ghc/compiler/typecheck/Inst.lhs index f7a8472..9f3c684 100644 --- a/ghc/compiler/typecheck/Inst.lhs +++ b/ghc/compiler/typecheck/Inst.lhs @@ -5,190 +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, tidyMoreInsts, - newDictsFromOld, newDicts, cloneDict, - newMethod, newMethodWithGivenTy, newMethodAtLoc, - newOverloadedLit, newIPDict, tcInstCall, + newDictsFromOld, newDicts, cloneDict, + newOverloadedLit, newIPDict, + newMethod, newMethodFromName, newMethodWithGivenTy, + tcInstClassOp, tcInstCall, tcInstDataCon, + tcSyntaxName, tcStdSyntaxName, tyVarsOfInst, tyVarsOfInsts, tyVarsOfLIE, - ipNamesOfInst, ipNamesOfInsts, predsOfInst, predsOfInsts, + ipNamesOfInst, ipNamesOfInsts, fdPredsOfInst, fdPredsOfInsts, instLoc, getDictClassTys, dictPred, - lookupInst, lookupSimpleInst, LookupInstResult(..), + lookupInst, LookupInstResult(..), isDict, isClassDict, isMethod, - isLinearInst, linearInstType, + isLinearInst, linearInstType, isIPDict, isInheritableInst, isTyVarDict, isStdClassTyVarDict, isMethodFor, instBindingRequired, instCanBeGeneralised, zonkInst, zonkInsts, instToId, instName, - InstOrigin(..), InstLoc, pprInstLoc + InstOrigin(..), InstLoc(..), pprInstLoc ) where #include "HsVersions.h" +import {-# SOURCE #-} TcExpr( tcCheckSigma ) + import HsSyn ( HsLit(..), HsOverLit(..), HsExpr(..) ) -import TcHsSyn ( TcExpr, TcId, TypecheckedHsExpr, - mkHsTyApp, mkHsDictApp, mkHsConApp, zonkId +import TcHsSyn ( TcExpr, TcId, TcIdSet, + mkHsTyApp, mkHsDictApp, mkHsConApp, zonkId, + mkCoercion, ExprCoFn ) -import TcMonad -import TcEnv ( TcIdSet, tcGetInstEnv, tcLookupId ) +import TcRnMonad +import TcEnv ( tcGetInstEnv, tcLookupId, tcLookupTyCon, checkWellStaged, topIdLvl ) import InstEnv ( InstLookupResult(..), lookupInstEnv ) -import TcMType ( zonkTcType, zonkTcTypes, zonkTcPredType, zapToType, - zonkTcThetaType, tcInstTyVar, tcInstType, +import TcMType ( zonkTcType, zonkTcTypes, zonkTcPredType, + zonkTcThetaType, tcInstTyVar, tcInstType, tcInstTyVars ) -import TcType ( Type, TcType, TcThetaType, TcPredType, TcTauType, TcTyVarSet, - SourceType(..), PredType, ThetaType, TyVarDetails(VanillaTv), - tcSplitForAllTys, tcSplitForAllTys, - tcSplitMethodTy, tcSplitPhiTy, tcFunArgTy, +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, - isClassPred, isTyVarClassPred, isLinearPred, + isClassPred, isTyVarClassPred, isLinearPred, getClassPredTys, getClassPredTys_maybe, mkPredName, - tidyType, tidyTypes, tidyFreeTyVars, - tcCmpType, tcCmpTypes, tcCmpPred + 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, mkTopTyVarSubst - ) +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 ( floatDataCon, doubleDataCon ) -import PrelNames( fromIntegerName, fromRationalName ) -import Util ( thenCmp, equalLength ) +import PrelNames( fromIntegerName, fromRationalName, rationalTyConName ) import BasicTypes( IPName(..), mapIPName, ipNameName ) - -import Bag +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 `tcCmpPred` pred2 -cmpInst (Dict _ _ _) other = LT - -cmpInst (Method _ _ _ _ _ _) (Dict _ _ _) = GT -cmpInst (Method _ id1 tys1 _ _ _) (Method _ id2 tys2 _ _ _) = (id1 `compare` id2) `thenCmp` (tys1 `tcCmpTypes` tys2) -cmpInst (Method _ _ _ _ _ _) other = LT - -cmpInst (LitInst _ lit1 ty1 _) (LitInst _ lit2 ty2 _) = (lit1 `compare` lit2) `thenCmp` (ty1 `tcCmpType` ty2) -cmpInst (LitInst _ _ _ _) other = GT - --- and they can only have HsInt or HsFracs in them. -\end{code} - Selection ~~~~~~~~~ @@ -210,22 +101,28 @@ 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. 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] @@ -239,6 +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} @@ -258,6 +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 @@ -308,46 +210,49 @@ 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 -cloneDict :: Inst -> NF_TcM Inst -cloneDict (Dict id ty loc) = tcGetUnique `thenNF_Tc` \ uniq -> - returnNF_Tc (Dict (setIdUnique id uniq) ty loc) +cloneDict :: Inst -> TcM Inst +cloneDict (Dict id ty loc) = newUnique `thenM` \ uniq -> + returnM (Dict (setIdUnique id uniq) ty loc) -newDictsFromOld :: Inst -> TcThetaType -> NF_TcM [Inst] +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 + 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 - -> NF_TcM (IPName Id, Inst) + -> TcM (IPName Id, Inst) newIPDict orig ip_name ty - = tcGetInstLoc orig `thenNF_Tc` \ inst_loc@(_,loc,_) -> - tcGetUnique `thenNF_Tc` \ uniq -> + = 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 - returnNF_Tc (mapIPName (\n -> id) ip_name, Dict id pred inst_loc) + returnM (mapIPName (\n -> id) ip_name, Dict id pred inst_loc) \end{code} + %************************************************************************ %* * \subsection{Building methods (calls of overloaded functions)} @@ -356,53 +261,90 @@ newIPDict orig ip_name ty \begin{code} -tcInstCall :: InstOrigin -> TcType -> NF_TcM (TypecheckedHsExpr -> TypecheckedHsExpr, LIE, TcType) +tcInstCall :: InstOrigin -> TcType -> TcM (ExprCoFn, 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 -> + = tcInstType VanillaTv fun_ty `thenM` \ (tyvars, theta, tau) -> + newDicts orig theta `thenM` \ dicts -> + extendLIEs dicts `thenM_` let inst_fn e = mkHsDictApp (mkHsTyApp e (mkTyVarTys tyvars)) (map instToId dicts) in - returnNF_Tc (inst_fn, mkLIE dicts, tau) - -newMethod :: InstOrigin - -> TcId - -> [TcType] - -> NF_TcM Inst -newMethod orig id tys - = -- Get the Id type and instantiate it at the specified types + 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 + tcInstTyVars VanillaTv (tvs ++ ex_tvs) `thenM` \ (all_tvs', ty_args', tenv) -> let - (tyvars, rho) = tcSplitForAllTys (idType id) - rho_ty = substTyWith tyvars tys rho - (pred, tau) = tcSplitMethodTy rho_ty + 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 - newMethodWithGivenTy orig id tys [pred] tau + 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) = 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) + returnM inst \end{code} In newOverloadedLit we convert directly to an Int or Integer if we @@ -414,38 +356,65 @@ cases (the rest are caught in lookupInst). newOverloadedLit :: InstOrigin -> HsOverLit -> TcType - -> NF_TcM (TcExpr, LIE) -newOverloadedLit orig lit expected_ty - | Just expr <- shortCutLit lit expected_ty - = returnNF_Tc (expr, emptyLIE) + -> 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 - = 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 + = 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 - returnNF_Tc (HsVar (instToId lit_inst), unitLIE lit_inst) + extendLIE lit_inst `thenM_` + returnM (HsVar (instToId lit_inst)) -shortCutLit :: HsOverLit -> TcType -> Maybe TcExpr -shortCutLit (HsIntegral i fi) ty - | isIntTy ty && inIntRange i && fi == fromIntegerName -- Short cut for Int +shortCutIntLit :: Integer -> TcType -> Maybe TcExpr +shortCutIntLit i ty + | isIntTy ty && inIntRange i -- Short cut for Int = Just (HsLit (HsInt i)) - | isIntegerTy ty && fi == fromIntegerName -- Short cut for Integer + | isIntegerTy ty -- Short cut for Integer = Just (HsLit (HsInteger i)) + | otherwise = Nothing -shortCutLit (HsFractional f fr) ty - | isFloatTy ty && fr == fromRationalName +shortCutFracLit :: Rational -> TcType -> Maybe TcExpr +shortCutFracLit f ty + | isFloatTy ty = Just (mkHsConApp floatDataCon [] [HsLit (HsFloatPrim f)]) - | isDoubleTy ty && fr == fromRationalName + | isDoubleTy ty = Just (mkHsConApp doubleDataCon [] [HsLit (HsDoublePrim f)]) + | otherwise = Nothing -shortCutLit lit ty - = Nothing +mkRatLit :: Rational -> TcM TcExpr +mkRatLit r + = tcLookupTyCon rationalTyConName `thenM` \ rat_tc -> + let + rational_ty = mkGenTyConApp rat_tc [] + in + returnM (HsLit (HsRat r rational_ty)) \end{code} @@ -460,27 +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} @@ -497,6 +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] @@ -527,6 +504,12 @@ tidyMoreInsts env 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} @@ -542,14 +525,16 @@ 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) - = getDOptsTc `thenNF_Tc` \ dflags -> - tcGetInstEnv `thenNF_Tc` \ inst_env -> +-- 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 @@ -558,37 +543,41 @@ 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 - Just (DoneTy ty) -> returnNF_Tc ty - Nothing -> tcInstTyVar VanillaTv 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 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 @@ -598,47 +587,104 @@ lookupInst inst@(Method _ id tys theta _ loc) -- [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)))) + | 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) - = 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)) + | 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} -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. + + +%************************************************************************ +%* * + Re-mappable syntax +%* * +%************************************************************************ + + +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: + + (>>) :: 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... + +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 +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) -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 +tcStdSyntaxName :: InstOrigin + -> TcType -- Type to instantiate it at + -> Name -- Standard name + -> TcM (Name, TcExpr) -- (Standard name, suitable expression) - other -> returnNF_Tc Nothing +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}