X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2Ftypecheck%2FTcSimplify.lhs;h=0af5ceb0a163b375dd4929671bbc68c2575f06e1;hb=4c6a3f787abcaed009a574196d82237d9ae64fc8;hp=4ba185f81c72536045a18c19e241bfdfe6f745da;hpb=996489295947877c5b2d6129e5d61043887391d9;p=ghc-hetmet.git diff --git a/compiler/typecheck/TcSimplify.lhs b/compiler/typecheck/TcSimplify.lhs index 4ba185f..0af5ceb 100644 --- a/compiler/typecheck/TcSimplify.lhs +++ b/compiler/typecheck/TcSimplify.lhs @@ -36,7 +36,6 @@ import TcRnMonad import Inst import TcEnv import InstEnv -import TcGadt import TcType import TcMType import TcIface @@ -65,7 +64,9 @@ import Util import UniqSet import SrcLoc import DynFlags +import FastString +import Control.Monad import Data.List \end{code} @@ -921,16 +922,15 @@ tcSimplifyCheck loc qtvs givens wanteds ----------------------------------------------------------- -- tcSimplifyCheckPat is used for existential pattern match tcSimplifyCheckPat :: InstLoc - -> [CoVar] -> [TcTyVar] -- Quantify over these -> [Inst] -- Given -> [Inst] -- Wanted -> TcM TcDictBinds -- Bindings -tcSimplifyCheckPat loc co_vars qtvs givens wanteds +tcSimplifyCheckPat loc qtvs givens wanteds = ASSERT( all isTcTyVar qtvs && all isSkolemTyVar qtvs ) do { traceTc (text "tcSimplifyCheckPat") ; (irreds, binds) <- gentleCheckLoop loc givens wanteds - ; implic_bind <- bindIrredsR loc qtvs co_vars givens irreds + ; implic_bind <- bindIrredsR loc qtvs givens irreds ; return (binds `unionBags` implic_bind) } ----------------------------------------------------------- @@ -938,13 +938,12 @@ bindIrreds :: InstLoc -> [TcTyVar] -> [Inst] -> [Inst] -> TcM TcDictBinds bindIrreds loc qtvs givens irreds - = bindIrredsR loc qtvs [] givens irreds + = bindIrredsR loc qtvs givens irreds -bindIrredsR :: InstLoc -> [TcTyVar] -> [CoVar] -> [Inst] -> [Inst] - -> TcM TcDictBinds +bindIrredsR :: InstLoc -> [TcTyVar] -> [Inst] -> [Inst] -> TcM TcDictBinds -- Make a binding that binds 'irreds', by generating an implication -- constraint for them, *and* throwing the constraint into the LIE -bindIrredsR loc qtvs co_vars givens irreds +bindIrredsR loc qtvs givens irreds | null irreds = return emptyBag | otherwise @@ -965,8 +964,7 @@ bindIrredsR loc qtvs co_vars givens irreds ; return real_irreds } else return irreds - ; let all_tvs = qtvs ++ co_vars -- Abstract over all these - ; (implics, bind) <- makeImplicationBind loc all_tvs givens' irreds' + ; (implics, bind) <- makeImplicationBind loc qtvs givens' irreds' -- This call does the real work -- If irreds' is empty, it does something sensible ; extendLIEs implics @@ -1000,7 +998,7 @@ makeImplicationBind loc all_tvs -- 'givens' must be a simple CoVar. This MUST be cleaned up. ; let name = mkInternalName uniq (mkVarOcc "ic") span - implic_inst = ImplicInst { tci_name = name, tci_reft = emptyRefinement, + implic_inst = ImplicInst { tci_name = name, tci_tyvars = all_tvs, tci_given = (eq_givens ++ dict_givens), tci_wanted = irreds, tci_loc = loc } @@ -1153,7 +1151,7 @@ Given the FD of Modular in this example, class improvement will instantiate t_a to 'a', where 'a' is the skolem from test5's signatures (due to the Modular s a predicate in that signature). If we don't zonk (Modular s t_a) in the givens, we will get into a loop as improveOne uses the unification engine -TcGadt.tcUnifyTys, which doesn't know about mutable type variables. +Unify.tcUnifyTys, which doesn't know about mutable type variables. Note [LOOP] @@ -1758,12 +1756,12 @@ reduceContext env wanteds ; let givens = red_givens env (given_eqs0, given_dicts0) = partition isEqInst givens (wanted_eqs0, wanted_non_eqs) = partition isEqInst wanteds - (wanted_implics0, wanted_dicts0) = partition isImplicInst wanted_non_eqs + (wanted_implics0, wanted_dicts) = partition isImplicInst wanted_non_eqs -- We want to add as wanted equalities those that (transitively) -- occur in superclass contexts of wanted class constraints. -- See Note [Ancestor Equalities] - ; ancestor_eqs <- ancestorEqualities wanted_dicts0 + ; ancestor_eqs <- ancestorEqualities wanted_dicts ; let wanted_eqs = wanted_eqs0 ++ ancestor_eqs ; traceTc $ text "reduceContext: ancestor eqs" <+> ppr ancestor_eqs @@ -1784,61 +1782,51 @@ reduceContext env wanteds -- *** ToDo: what to do with the "extra_givens"? For the -- moment I'm simply discarding them, which is probably wrong - -- 7. Normalise the *wanted* *dictionary* constraints - -- wrt. the toplevel and given equations - -- NB: normalisation includes zonking as part of what it does - -- so it's important to do it after any unifications - -- that happened as a result of the addGivens - ; (wanted_dicts,normalise_binds1) <- normaliseWantedDicts given_eqs wanted_dicts0 - -- 6. Solve the *wanted* *dictionary* constraints (not implications) -- This may expose some further equational constraints... ; (avails, extra_eqs) <- getLIE (reduceList env wanted_dicts init_state) - ; (dict_binds, bound_dicts, dict_irreds) <- extractResults avails wanted_dicts + ; (dict_binds, bound_dicts, dict_irreds) + <- extractResults avails wanted_dicts ; traceTc $ text "reduceContext extractresults" <+> vcat - [ppr avails,ppr wanted_dicts,ppr dict_binds] - - -- *** ToDo: what to do with the "extra_eqs"? For the - -- moment I'm simply discarding them, which is probably wrong + [ppr avails, ppr wanted_dicts, ppr dict_binds] -- Solve the wanted *implications*. In doing so, we can provide -- as "given" all the dicts that were originally given, -- *or* for which we now have bindings, -- *or* which are now irreds - ; let implic_env = env { red_givens = givens ++ bound_dicts ++ dict_irreds } - ; (implic_binds_s, implic_irreds_s) <- mapAndUnzipM (reduceImplication implic_env) wanted_implics0 + ; let implic_env = env { red_givens = givens ++ bound_dicts + ++ dict_irreds } + ; (implic_binds_s, implic_irreds_s) + <- mapAndUnzipM (reduceImplication implic_env) wanted_implics0 ; let implic_binds = unionManyBags implic_binds_s implic_irreds = concat implic_irreds_s - -- 3. Solve the *wanted* *equation* constraints - ; eq_irreds0 <- solveWantedEqs given_eqs wanted_eqs - - -- 4. Normalise the *wanted* equality constraints with respect to - -- each other - ; eq_irreds <- normaliseWantedEqs eq_irreds0 + -- Normalise the wanted equality constraints + ; eq_irreds <- normaliseWantedEqs given_eqs (wanted_eqs ++ extra_eqs) - -- 8. Substitute the wanted *equations* in the wanted *dictionaries* + -- Normalise the wanted dictionaries ; let irreds = dict_irreds ++ implic_irreds - ; (norm_irreds, normalise_binds2) <- substEqInDictInsts True {-wanted-} - eq_irreds irreds + eqs = eq_irreds ++ given_eqs + ; (norm_irreds, normalise_binds) <- normaliseWantedDicts eqs irreds - -- 9. eliminate the artificial skolem constants introduced in 1. --- ; eliminate_skolems - - -- Figure out whether we should go round again - -- My current plan is to see if any of the mutable tyvars in - -- givens or irreds has been filled in by improvement. - -- If so, there is merit in going around again, because - -- we may make further progress + -- Figure out whether we should go round again. We do so in either + -- two cases: + -- (1) If any of the mutable tyvars in givens or irreds has been + -- filled in by improvement, there is merit in going around + -- again, because we may make further progress. + -- (2) If we managed to normalise any dicts, there is merit in going + -- around gain, because reduceList may be able to get further. -- - -- ToDo: is it only mutable stuff? We may have exposed new + -- ToDo: We may have exposed new -- equality constraints and should probably go round again -- then as well. But currently we are dropping them on the -- floor anyway. ; let all_irreds = norm_irreds ++ eq_irreds - ; improved <- anyM isFilledMetaTyVar $ varSetElems $ - tyVarsOfInsts (givens ++ all_irreds) + ; improvedMetaTy <- anyM isFilledMetaTyVar $ varSetElems $ + tyVarsOfInsts (givens ++ all_irreds) + ; let improvedDicts = not $ isEmptyBag normalise_binds + improved = improvedMetaTy || improvedDicts -- The old plan (fragile) -- improveed = availsImproved avails @@ -1863,8 +1851,7 @@ reduceContext env wanteds ])) ; return (improved, - given_binds `unionBags` normalise_binds1 - `unionBags` normalise_binds2 + given_binds `unionBags` normalise_binds `unionBags` dict_binds `unionBags` implic_binds, all_irreds, @@ -1920,12 +1907,9 @@ reduceList :: RedEnv -> [Inst] -> Avails -> TcM Avails reduceList env@(RedEnv {red_stack = (n,stk)}) wanteds state = do { traceTc (text "reduceList " <+> (ppr wanteds $$ ppr state)) ; dopts <- getDOpts -#ifdef DEBUG - ; if n > 8 then + ; when (debugIsOn && (n > 8)) $ do dumpTcRn (hang (ptext SLIT("Interesting! Context reduction stack depth") <+> int n) 2 (ifPprDebug (nest 2 (pprStack stk)))) - else return () -#endif ; if n >= ctxtStkDepth dopts then failWithTc (reduceDepthErr n stk) else @@ -2137,7 +2121,7 @@ Note that -- reduceImplication env orig_implic@(ImplicInst { tci_name = name, tci_loc = inst_loc, - tci_tyvars = tvs, tci_reft = emptyRefinement, + tci_tyvars = tvs, tci_given = extra_givens, tci_wanted = wanteds }) = do { -- Solve the sub-problem ; let try_me inst = ReduceMe AddSCs -- Note [Freeness and implications] @@ -2942,14 +2926,13 @@ report_no_instances tidy_env mb_what insts | not (isClassDict wanted) = Left wanted | otherwise = case lookupInstEnv inst_envs clas tys of + ([], _) -> Left wanted -- No match -- The case of exactly one match and no unifiers means a -- successful lookup. That can't happen here, because dicts -- only end up here if they didn't match in Inst.lookupInst -#ifdef DEBUG - ([m],[]) -> pprPanic "reportNoInstance" (ppr wanted) -#endif - ([], _) -> Left wanted -- No match - res -> Right (mk_overlap_msg wanted res) + ([m],[]) + | debugIsOn -> pprPanic "reportNoInstance" (ppr wanted) + res -> Right (mk_overlap_msg wanted res) where (clas,tys) = getDictClassTys wanted