X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2FdeSugar%2FDsBinds.lhs;h=c886c8ef6bae478161b78a4138af630395c0f4fd;hp=2c6f361ca070737fa89638fcfc93b82da51f33ce;hb=d2ce0f52d42edf32bb9f13796e6ba6edba8bd516;hpb=0084ab49ab3c0123c4b7f9523d092af45bccfd41 diff --git a/compiler/deSugar/DsBinds.lhs b/compiler/deSugar/DsBinds.lhs index 2c6f361..c886c8e 100644 --- a/compiler/deSugar/DsBinds.lhs +++ b/compiler/deSugar/DsBinds.lhs @@ -11,8 +11,8 @@ lower levels it is preserved with @let@/@letrec@s). \begin{code} module DsBinds ( dsTopLHsBinds, dsLHsBinds, decomposeRuleLhs, - dsCoercion, - AutoScc(..) + dsHsWrapper, dsTcEvBinds, dsEvBinds, wrapDsEvBinds, + DsEvBind(..), AutoScc(..) ) where #include "HsVersions.h" @@ -32,30 +32,34 @@ import CoreUtils import CoreArity ( etaExpand ) import CoreUnfold import CoreFVs +import Digraph import TcType +import Type import TysPrim ( anyTypeOfKind ) import CostCentre import Module import Id +import TyCon ( tyConDataCons ) +import Class +import DataCon ( dataConRepType ) import Name ( localiseName ) import MkId ( seqId ) -import Var ( Var, TyVar, tyVarKind ) -import IdInfo ( vanillaIdInfo ) +import Var import VarSet import Rules import VarEnv import Outputable import SrcLoc import Maybes +import OrdList import Bag import BasicTypes hiding ( TopLevel ) import FastString -import StaticFlags ( opt_DsMultiTyVar ) -import Util ( count, lengthExceeds ) +-- import StaticFlags ( opt_DsMultiTyVar ) +import Util import MonadUtils -import Control.Monad \end{code} %************************************************************************ @@ -66,31 +70,27 @@ import Control.Monad \begin{code} dsTopLHsBinds :: AutoScc -> LHsBinds Id -> DsM [(Id,CoreExpr)] -dsTopLHsBinds auto_scc binds = ds_lhs_binds auto_scc binds +dsTopLHsBinds auto_scc binds = do { binds' <- ds_lhs_binds auto_scc binds + ; return (fromOL binds') } dsLHsBinds :: LHsBinds Id -> DsM [(Id,CoreExpr)] -dsLHsBinds binds = ds_lhs_binds NoSccs binds - +dsLHsBinds binds = do { binds' <- ds_lhs_binds NoSccs binds + ; return (fromOL binds') } ------------------------ -ds_lhs_binds :: AutoScc -> LHsBinds Id -> DsM [(Id,CoreExpr)] +ds_lhs_binds :: AutoScc -> LHsBinds Id -> DsM (OrdList (Id,CoreExpr)) -- scc annotation policy (see below) -ds_lhs_binds auto_scc binds = foldM (dsLHsBind auto_scc) [] (bagToList binds) +ds_lhs_binds auto_scc binds = do { ds_bs <- mapBagM (dsLHsBind auto_scc) binds + ; return (foldBag appOL id nilOL ds_bs) } -dsLHsBind :: AutoScc - -> [(Id,CoreExpr)] -- Put this on the end (avoid quadratic append) - -> LHsBind Id - -> DsM [(Id,CoreExpr)] -- Result -dsLHsBind auto_scc rest (L loc bind) - = putSrcSpanDs loc $ dsHsBind auto_scc rest bind +dsLHsBind :: AutoScc -> LHsBind Id -> DsM (OrdList (Id,CoreExpr)) +dsLHsBind auto_scc (L loc bind) + = putSrcSpanDs loc $ dsHsBind auto_scc bind -dsHsBind :: AutoScc - -> [(Id,CoreExpr)] -- Put this on the end (avoid quadratic append) - -> HsBind Id - -> DsM [(Id,CoreExpr)] -- Result +dsHsBind :: AutoScc -> HsBind Id -> DsM (OrdList (Id,CoreExpr)) -dsHsBind _ rest (VarBind { var_id = var, var_rhs = expr, var_inline = inline_regardless }) +dsHsBind _ (VarBind { var_id = var, var_rhs = expr, var_inline = inline_regardless }) = do { core_expr <- dsLExpr expr -- Dictionary bindings are always VarBinds, @@ -99,25 +99,30 @@ dsHsBind _ rest (VarBind { var_id = var, var_rhs = expr, var_inline = inline_reg ; let var' | inline_regardless = var `setIdUnfolding` mkCompulsoryUnfolding core_expr' | otherwise = var - ; return ((var', core_expr') : rest) } + ; return (unitOL (var', core_expr')) } -dsHsBind _ rest - (FunBind { fun_id = L _ fun, fun_matches = matches, - fun_co_fn = co_fn, fun_tick = tick, fun_infix = inf }) +dsHsBind _ (FunBind { fun_id = L _ fun, fun_matches = matches + , fun_co_fn = co_fn, fun_tick = tick + , fun_infix = inf }) = do { (args, body) <- matchWrapper (FunRhs (idName fun) inf) matches ; body' <- mkOptTickBox tick body - ; wrap_fn' <- dsCoercion co_fn - ; return ((fun, wrap_fn' (mkLams args body')) : rest) } + ; wrap_fn' <- dsHsWrapper co_fn + ; return (unitOL (fun, wrap_fn' (mkLams args body'))) } -dsHsBind _ rest - (PatBind { pat_lhs = pat, pat_rhs = grhss, pat_rhs_ty = ty }) +dsHsBind _ (PatBind { pat_lhs = pat, pat_rhs = grhss, pat_rhs_ty = ty }) = do { body_expr <- dsGuarded grhss ty ; sel_binds <- mkSelectorBinds pat body_expr - ; return (sel_binds ++ rest) } + ; return (toOL sel_binds) } -dsHsBind auto_scc rest (AbsBinds [] [] exports binds) - = do { core_prs <- ds_lhs_binds NoSccs binds - ; let env = mkABEnv exports +{- +dsHsBind auto_scc (AbsBinds { abs_tvs = [], abs_ev_vars = [] + , abs_exports = exports, abs_ev_binds = ev_binds + , abs_binds = binds }) + = do { bind_prs <- ds_lhs_binds NoSccs binds + ; ds_ev_binds <- dsTcEvBinds ev_binds + + ; let core_prs = addEvPairs ds_ev_binds bind_prs + env = mkABEnv exports do_one (lcl_id, rhs) | Just (_, gbl_id, _, spec_prags) <- lookupVarEnv env lcl_id = do { let rhs' = addAutoScc auto_scc gbl_id rhs @@ -137,13 +142,19 @@ dsHsBind auto_scc rest (AbsBinds [] [] exports binds) -- because we can rely on the enclosing dsBind to wrap in Rec -dsHsBind auto_scc rest (AbsBinds tyvars [] exports binds) +dsHsBind auto_scc rest (AbsBinds { abs_tvs = tyvars, abs_ev_vars = [] + , abs_exports = exports, abs_ev_binds = ev_binds + , abs_binds = binds }) | opt_DsMultiTyVar -- This (static) debug flag just lets us -- switch on and off this optimisation to -- see if it has any impact; it is on by default + , allOL isLazyEvBind ev_binds = -- Note [Abstracting over tyvars only] - do { core_prs <- ds_lhs_binds NoSccs binds - ; let arby_env = mkArbitraryTypeEnv tyvars exports + do { bind_prs <- ds_lhs_binds NoSccs binds + ; ds_ev_binds <- dsTcEvBinds ev_binds + + ; let core_prs = addEvPairs ds_ev_binds bind_prs + arby_env = mkArbitraryTypeEnv tyvars exports bndrs = mkVarSet (map fst core_prs) add_lets | core_prs `lengthExceeds` 10 = add_some @@ -179,21 +190,25 @@ dsHsBind auto_scc rest (AbsBinds tyvars [] exports binds) ; (_, core_prs') <- fixDs (\ ~(lg_binds, _) -> mapAndUnzipM (do_one lg_binds) core_prs) ; return (concat core_prs' ++ rest) } +-} - -- Another common case: one exported variable + -- A common case: one exported variable -- Non-recursive bindings come through this way -- So do self-recursive bindings, and recursive bindings -- that have been chopped up with type signatures -dsHsBind auto_scc rest - (AbsBinds all_tyvars dicts [(tyvars, global, local, prags)] binds) +dsHsBind auto_scc (AbsBinds { abs_tvs = all_tyvars, abs_ev_vars = dicts + , abs_exports = [(tyvars, global, local, prags)] + , abs_ev_binds = ev_binds, abs_binds = binds }) = ASSERT( all (`elem` tyvars) all_tyvars ) - do { core_prs <- ds_lhs_binds NoSccs binds + do { bind_prs <- ds_lhs_binds NoSccs binds + ; ds_ev_binds <- dsTcEvBinds ev_binds - ; let -- Always treat the binds as recursive, because the - -- typechecker makes rather mixed-up dictionary bindings - core_bind = Rec core_prs + ; let core_bind = Rec (fromOL bind_prs) rhs = addAutoScc auto_scc global $ - mkLams tyvars $ mkLams dicts $ Let core_bind (Var local) + mkLams tyvars $ mkLams dicts $ + wrapDsEvBinds ds_ev_binds $ + Let core_bind $ + Var local ; (spec_binds, rules) <- dsSpecs global rhs prags @@ -201,22 +216,27 @@ dsHsBind auto_scc rest main_bind = makeCorePair global' (isDefaultMethod prags) (dictArity dicts) rhs - ; return (main_bind : spec_binds ++ rest) } + ; return (main_bind `consOL` spec_binds) } -dsHsBind auto_scc rest (AbsBinds all_tyvars dicts exports binds) - = do { core_prs <- ds_lhs_binds NoSccs binds +dsHsBind auto_scc (AbsBinds { abs_tvs = all_tyvars, abs_ev_vars = dicts + , abs_exports = exports, abs_ev_binds = ev_binds + , abs_binds = binds }) + = do { bind_prs <- ds_lhs_binds NoSccs binds + ; ds_ev_binds <- dsTcEvBinds ev_binds ; let env = mkABEnv exports do_one (lcl_id,rhs) | Just (_, gbl_id, _, _prags) <- lookupVarEnv env lcl_id = (lcl_id, addAutoScc auto_scc gbl_id rhs) | otherwise = (lcl_id,rhs) - -- Rec because of mixed-up dictionary bindings - core_bind = Rec (map do_one core_prs) + core_bind = Rec (map do_one (fromOL bind_prs)) + -- Monomorphic recursion possible, hence Rec tup_expr = mkBigCoreVarTup locals tup_ty = exprType tup_expr poly_tup_rhs = mkLams all_tyvars $ mkLams dicts $ - Let core_bind tup_expr + wrapDsEvBinds ds_ev_binds $ + Let core_bind $ + tup_expr locals = [local | (_, _, local, _) <- exports] local_tys = map idType locals @@ -237,7 +257,7 @@ dsHsBind auto_scc rest (AbsBinds all_tyvars dicts exports binds) (Let (NonRec poly_tup_id poly_tup_rhs) rhs) spec_prags ; let global' = addIdSpecialisations global rules - ; return ((global', rhs) : spec_binds) } + ; return ((global', rhs) `consOL` spec_binds) } where mk_ty_arg all_tyvar | all_tyvar `elem` tyvars = mkTyVarTy all_tyvar @@ -246,9 +266,89 @@ dsHsBind auto_scc rest (AbsBinds all_tyvars dicts exports binds) ; export_binds_s <- mapM mk_bind (exports `zip` [0..]) -- Don't scc (auto-)annotate the tuple itself. - ; return ((poly_tup_id, poly_tup_rhs) : - (concat export_binds_s ++ rest)) } + ; return ((poly_tup_id, poly_tup_rhs) `consOL` + concatOL export_binds_s) } + +-------------------------------------- +data DsEvBind + = LetEvBind -- Dictionary or coercion + CoreBind -- recursive or non-recursive + | CaseEvBind -- Coercion binding by superclass selection + -- Desugars to case d of d { K _ g _ _ _ -> ... } + DictId -- b The dictionary + AltCon -- K Its constructor + [CoreBndr] -- _ g _ _ _ The binders in the alternative + +wrapDsEvBinds :: [DsEvBind] -> CoreExpr -> CoreExpr +wrapDsEvBinds ds_ev_binds body = foldr wrap_one body ds_ev_binds + where + body_ty = exprType body + wrap_one (LetEvBind b) body = Let b body + wrap_one (CaseEvBind x k xs) body = Case (Var x) x body_ty [(k,xs,body)] + +dsTcEvBinds :: TcEvBinds -> DsM [DsEvBind] +dsTcEvBinds (TcEvBinds {}) = panic "dsEvBinds" -- Zonker has got rid of this +dsTcEvBinds (EvBinds bs) = dsEvBinds bs + +dsEvBinds :: Bag EvBind -> DsM [DsEvBind] +dsEvBinds bs = return (map dsEvGroup sccs) + where + sccs :: [SCC EvBind] + sccs = stronglyConnCompFromEdgedVertices edges + + edges :: [(EvBind, EvVar, [EvVar])] + edges = foldrBag ((:) . mk_node) [] bs + + mk_node :: EvBind -> (EvBind, EvVar, [EvVar]) + mk_node b@(EvBind var term) = (b, var, free_vars_of term) + + free_vars_of :: EvTerm -> [EvVar] + free_vars_of (EvId v) = [v] + free_vars_of (EvCast v co) = v : varSetElems (tyVarsOfType co) + free_vars_of (EvCoercion co) = varSetElems (tyVarsOfType co) + free_vars_of (EvDFunApp _ _ vs) = vs + free_vars_of (EvSuperClass d _) = [d] + +dsEvGroup :: SCC EvBind -> DsEvBind +dsEvGroup (AcyclicSCC (EvBind co_var (EvSuperClass dict n))) + | isCoVar co_var -- An equality superclass + = ASSERT( null other_data_cons ) + CaseEvBind dict (DataAlt data_con) bndrs + where + (cls, tys) = getClassPredTys (evVarPred dict) + (data_con:other_data_cons) = tyConDataCons (classTyCon cls) + (ex_tvs, theta, rho) = tcSplitSigmaTy (applyTys (dataConRepType data_con) tys) + (arg_tys, _) = splitFunTys rho + bndrs = ex_tvs ++ map mk_wild_pred (theta `zip` [0..]) + ++ map mkWildValBinder arg_tys + mk_wild_pred (p, i) | i==n = ASSERT( p `tcEqPred` (coVarPred co_var)) + co_var + | otherwise = mkWildEvBinder p + +dsEvGroup (AcyclicSCC (EvBind v r)) + = LetEvBind (NonRec v (dsEvTerm r)) + +dsEvGroup (CyclicSCC bs) + = LetEvBind (Rec (map ds_pair bs)) + where + ds_pair (EvBind v r) = (v, dsEvTerm r) + +dsEvTerm :: EvTerm -> CoreExpr +dsEvTerm (EvId v) = Var v +dsEvTerm (EvCast v co) = Cast (Var v) co +dsEvTerm (EvDFunApp df tys vars) = Var df `mkTyApps` tys `mkVarApps` vars +dsEvTerm (EvCoercion co) = Type co +dsEvTerm (EvSuperClass d n) + = ASSERT( isClassPred (classSCTheta cls !! n) ) + -- We can only select *dictionary* superclasses + -- in terms. Equality superclasses are dealt with + -- in dsEvGroup, where they can generate a case expression + Var sc_sel_id `mkTyApps` tys `App` Var d + where + sc_sel_id = classSCSelId cls n -- Zero-indexed + (cls, tys) = getClassPredTys (evVarPred d) + ------------------------ makeCorePair :: Id -> Bool -> Arity -> CoreExpr -> (Id, CoreExpr) makeCorePair gbl_id is_default_method dict_arity rhs @@ -445,34 +545,36 @@ Note that dsSpecs :: Id -- The polymorphic Id -> CoreExpr -- Its rhs -> TcSpecPrags - -> DsM ( [(Id,CoreExpr)] -- Binding for specialised Ids + -> DsM ( OrdList (Id,CoreExpr) -- Binding for specialised Ids , [CoreRule] ) -- Rules for the Global Ids -- See Note [Implementing SPECIALISE pragmas] dsSpecs poly_id poly_rhs prags = case prags of - IsDefaultMethod -> return ([], []) + IsDefaultMethod -> return (nilOL, []) SpecPrags sps -> do { pairs <- mapMaybeM spec_one sps ; let (spec_binds_s, rules) = unzip pairs - ; return (concat spec_binds_s, rules) } + ; return (concatOL spec_binds_s, rules) } where - spec_one :: Located TcSpecPrag -> DsM (Maybe ([(Id,CoreExpr)], CoreRule)) + spec_one :: Located TcSpecPrag -> DsM (Maybe (OrdList (Id,CoreExpr), CoreRule)) spec_one (L loc (SpecPrag spec_co spec_inl)) = putSrcSpanDs loc $ do { let poly_name = idName poly_id ; spec_name <- newLocalName poly_name - ; wrap_fn <- dsCoercion spec_co - ; let ds_spec_expr = wrap_fn (Var poly_id) - spec_ty = exprType ds_spec_expr - ; case decomposeRuleLhs ds_spec_expr of { + ; wrap_fn <- dsHsWrapper spec_co + ; let (bndrs, ds_lhs) = collectBinders (wrap_fn (Var poly_id)) + spec_ty = mkPiTypes bndrs (exprType ds_lhs) + ; case decomposeRuleLhs ds_lhs of { Nothing -> do { warnDs (decomp_msg spec_co) ; return Nothing } ; - Just (bndrs, _fn, args) -> + Just (_fn, args) -> -- Check for dead binders: Note [Unused spec binders] - case filter isDeadBinder bndrs of { - bs | not (null bs) -> do { warnDs (dead_msg bs); return Nothing } - | otherwise -> do + let arg_fvs = exprsFreeVars args + bad_bndrs = filterOut (`elemVarSet` arg_fvs) bndrs + in if not (null bad_bndrs) + then do { warnDs (dead_msg bad_bndrs); return Nothing } + else do { (spec_unf, unf_pairs) <- specUnfolding wrap_fn spec_ty (realIdUnfolding poly_id) @@ -486,7 +588,7 @@ dsSpecs poly_id poly_rhs prags extra_dict_bndrs = [ mkLocalId (localiseName (idName d)) (idType d) -- See Note [Constant rule dicts] - | d <- varSetElems (exprFreeVars ds_spec_expr) + | d <- varSetElems (arg_fvs `delVarSetList` bndrs) , isDictId d] rule = mkLocalRule (mkFastString ("SPEC " ++ showSDoc (ppr poly_name))) @@ -497,8 +599,8 @@ dsSpecs poly_id poly_rhs prags spec_rhs = wrap_fn poly_rhs spec_pair = makeCorePair spec_id False (dictArity bndrs) spec_rhs - ; return (Just (spec_pair : unf_pairs, rule)) - } } } } + ; return (Just (spec_pair `consOL` unf_pairs, rule)) + } } } dead_msg bs = vcat [ sep [ptext (sLit "Useless constraint") <> plural bs <+> ptext (sLit "in specialied type:"), @@ -512,14 +614,15 @@ dsSpecs poly_id poly_rhs prags specUnfolding :: (CoreExpr -> CoreExpr) -> Type - -> Unfolding -> DsM (Unfolding, [(Id,CoreExpr)]) + -> Unfolding -> DsM (Unfolding, OrdList (Id,CoreExpr)) specUnfolding wrap_fn spec_ty (DFunUnfolding _ _ ops) = do { let spec_rhss = map wrap_fn ops ; spec_ids <- mapM (mkSysLocalM (fsLit "spec") . exprType) spec_rhss - ; return (mkDFunUnfolding spec_ty (map Var spec_ids), spec_ids `zip` spec_rhss) } + ; return (mkDFunUnfolding spec_ty (map Var spec_ids), toOL (spec_ids `zip` spec_rhss)) } specUnfolding _ _ _ - = return (noUnfolding, []) + = return (noUnfolding, nilOL) +{- mkArbitraryTypeEnv :: [TyVar] -> [([TyVar], a, b, c)] -> TyVarEnv Type -- If any of the tyvars is missing from any of the lists in -- the second arg, return a binding in the result @@ -535,6 +638,7 @@ mkArbitraryTypeEnv tyvars exports , not (tv `elemVarEnv` env)] extend env tv = extendVarEnv env tv (dsMkArbitraryType tv) +-} dsMkArbitraryType :: TcTyVar -> Type dsMkArbitraryType tv = anyTypeOfKind (tyVarKind tv) @@ -587,37 +691,51 @@ as the old one, but with an Internal name and no IdInfo. %************************************************************************ \begin{code} -decomposeRuleLhs :: CoreExpr -> Maybe ([Var], Id, [CoreExpr]) +decomposeRuleLhs :: CoreExpr -> Maybe (Id, [CoreExpr]) -- Take apart the LHS of a RULE. It's suuposed to look like -- /\a. f a Int dOrdInt -- or /\a.\d:Ord a. let { dl::Ord [a] = dOrdList a d } in f [a] dl -- That is, the RULE binders are lambda-bound -- Returns Nothing if the LHS isn't of the expected shape decomposeRuleLhs lhs - = case collectArgs body of - (Var fn, args) -> Just (bndrs, fn, args) + = -- Note [Simplifying the left-hand side of a RULE] + case collectArgs (simpleOptExpr lhs) of + (Var fn, args) -> Just (fn, args) (Case scrut bndr ty [(DEFAULT, _, body)], args) | isDeadBinder bndr -- Note [Matching seqId] - -> Just (bndrs, seqId, args' ++ args) + -> Just (seqId, args' ++ args) where args' = [Type (idType bndr), Type ty, scrut, body] _other -> Nothing -- Unexpected shape - where - (bndrs, body) = collectBinders (simpleOptExpr lhs) - -- simpleOptExpr occurrence-analyses and simplifies the lhs - -- and thereby - -- (a) identifies unused binders: Note [Unused spec binders] - -- (b) sorts dict bindings into NonRecs - -- so they can be inlined by 'decomp' - -- (c) substitute trivial lets so that they don't get in the way - -- Note that we substitute the function too; we might - -- have this as a LHS: let f71 = M.f Int in f71 - -- NB: tcSimplifyRuleLhs is very careful not to generate complicated - -- dictionary expressions that we might have to match \end{code} +Note [Simplifying the left-hand side of a RULE] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +simpleOptExpr occurrence-analyses and simplifies the lhs +and thereby +(a) sorts dict bindings into NonRecs and inlines them +(b) substitute trivial lets so that they don't get in the way + Note that we substitute the function too; we might + have this as a LHS: let f71 = M.f Int in f71 +(c) does eta reduction + +For (c) consider the fold/build rule, which without simplification +looked like: + fold k z (build (/\a. g a)) ==> ... +This doesn't match unless you do eta reduction on the build argument. +Similarly for a LHS like + augment g (build h) +we do not want to get + augment (\a. g a) (build h) +otherwise we don't match when given an argument like + augment (\a. h a a) (build h) + +NB: tcSimplifyRuleLhs is very careful not to generate complicated + dictionary expressions that we might have to match + + Note [Matching seqId] ~~~~~~~~~~~~~~~~~~~ The desugarer turns (seq e r) into (case e of _ -> r), via a special-case hack @@ -679,19 +797,16 @@ addDictScc _ rhs = return rhs \begin{code} -dsCoercion :: HsWrapper -> DsM (CoreExpr -> CoreExpr) -dsCoercion WpHole = return (\e -> e) -dsCoercion (WpCompose c1 c2) = do { k1 <- dsCoercion c1 - ; k2 <- dsCoercion c2 - ; return (k1 . k2) } -dsCoercion (WpCast co) = return (\e -> Cast e co) -dsCoercion (WpLam id) = return (\e -> Lam id e) -dsCoercion (WpTyLam tv) = return (\e -> Lam tv e) -dsCoercion (WpApp v) | isTyVar v -- Probably a coercion var - = return (\e -> App e (Type (mkTyVarTy v))) - | otherwise - = return (\e -> App e (Var v)) -dsCoercion (WpTyApp ty) = return (\e -> App e (Type ty)) -dsCoercion (WpLet bs) = do { prs <- dsLHsBinds bs - ; return (\e -> Let (Rec prs) e) } +dsHsWrapper :: HsWrapper -> DsM (CoreExpr -> CoreExpr) +dsHsWrapper WpHole = return (\e -> e) +dsHsWrapper (WpTyApp ty) = return (\e -> App e (Type ty)) +dsHsWrapper (WpLet ev_binds) = do { ds_ev_binds <- dsTcEvBinds ev_binds + ; return (wrapDsEvBinds ds_ev_binds) } +dsHsWrapper (WpCompose c1 c2) = do { k1 <- dsHsWrapper c1 + ; k2 <- dsHsWrapper c2 + ; return (k1 . k2) } +dsHsWrapper (WpCast co) = return (\e -> Cast e co) +dsHsWrapper (WpEvLam ev) = return (\e -> Lam ev e) +dsHsWrapper (WpTyLam tv) = return (\e -> Lam tv e) +dsHsWrapper (WpEvApp evtrm) = return (\e -> App e (dsEvTerm evtrm)) \end{code}