X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2Frename%2FRnExpr.lhs;h=a496c66daa3f24f2e4a4094c720a5c98273b82dd;hp=ba6b0e0a29f6a2826d1629cfc022ba7bcfef5448;hb=67cb409159fa9136dff942b8baaec25909416022;hpb=fe784e7dfffa8b876ed738306a82bf4bdcfd8be7 diff --git a/compiler/rename/RnExpr.lhs b/compiler/rename/RnExpr.lhs index ba6b0e0..a496c66 100644 --- a/compiler/rename/RnExpr.lhs +++ b/compiler/rename/RnExpr.lhs @@ -36,14 +36,15 @@ import RnTypes ( rnHsTypeFVs, import RnPat (rnOverLit, rnPatsAndThen_LocalRightwards, rnBindPat, localRecNameMaker, rnLit, rnHsRecFields_Con, rnHsRecFields_Update, checkTupSize) +import RdrName ( mkRdrUnqual ) import DynFlags ( DynFlag(..) ) import BasicTypes ( FixityDirection(..) ) import SrcLoc ( SrcSpan ) import PrelNames ( thFAKE, hasKey, assertIdKey, assertErrorName, loopAName, choiceAName, appAName, arrAName, composeAName, firstAName, - negateName, thenMName, bindMName, failMName ) + negateName, thenMName, bindMName, failMName, groupWithName ) -import Name ( Name, nameOccName, nameIsLocalOrFrom ) +import Name ( Name, nameOccName, nameModule, nameIsLocalOrFrom ) import NameSet import UniqFM import RdrName ( RdrName, extendLocalRdrEnv, lookupLocalRdrEnv, hideSomeUnquals ) @@ -55,7 +56,7 @@ import Util ( isSingleton ) import ListSetOps ( removeDups ) import Maybes ( expectJust ) import Outputable -import SrcLoc ( Located(..), unLoc, getLoc ) +import SrcLoc ( Located(..), unLoc, getLoc, noLoc ) import FastString import List ( unzip4 ) @@ -477,7 +478,9 @@ methodNamesStmt (RecStmt stmts _ _ _ _) = methodNamesStmts stmts `addOneFV` loopAName methodNamesStmt (LetStmt b) = emptyFVs methodNamesStmt (ParStmt ss) = emptyFVs - -- ParStmt can't occur in commands, but it's not convenient to error +methodNamesStmt (TransformStmt _ _ _) = emptyFVs +methodNamesStmt (GroupStmt _ _) = emptyFVs + -- ParStmt, TransformStmt and GroupStmt can't occur in commands, but it's not convenient to error -- here so we just do what's convenient \end{code} @@ -588,13 +591,12 @@ rnNormalStmts :: HsStmtContext Name -> [LStmt RdrName] -- Implements nested scopes rnNormalStmts ctxt [] thing_inside - = do { (thing, fvs) <- thing_inside + = do { (thing, fvs) <- thing_inside ; return (([],thing), fvs) } rnNormalStmts ctxt (L loc stmt : stmts) thing_inside - = do { ((stmt', (stmts', thing)), fvs) - <- rnStmt ctxt stmt $ - rnNormalStmts ctxt stmts thing_inside + = do { ((stmt', (stmts', thing)), fvs) <- rnStmt ctxt stmt $ + rnNormalStmts ctxt stmts thing_inside ; return (((L loc stmt' : stmts'), thing), fvs) } @@ -621,12 +623,11 @@ rnStmt ctxt (BindStmt pat expr _ _) thing_inside -- fv_expr shouldn't really be filtered by the rnPatsAndThen -- but it does not matter because the names are unique -rnStmt ctxt (LetStmt binds) thing_inside - = do { checkErr (ok ctxt binds) - (badIpBinds (ptext SLIT("a parallel list comprehension:")) binds) - ; rnLocalBindsAndThen binds $ \ binds' -> do - { (thing, fvs) <- thing_inside - ; return ((LetStmt binds', thing), fvs) }} +rnStmt ctxt (LetStmt binds) thing_inside = do + checkErr (ok ctxt binds) (badIpBinds (ptext SLIT("a parallel list comprehension:")) binds) + rnLocalBindsAndThen binds $ \binds' -> do + (thing, fvs) <- thing_inside + return ((LetStmt binds', thing), fvs) where -- We do not allow implicit-parameter bindings in a parallel -- list comprehension. I'm not sure what it might mean. @@ -649,58 +650,163 @@ rnStmt ctxt (RecStmt rec_stmts _ _ _ _) thing_inside where doc = text "In a recursive do statement" +rnStmt ctxt (TransformStmt (stmts, _) usingExpr maybeByExpr) thing_inside = do + checkIsTransformableListComp ctxt + + (usingExpr', fv_usingExpr) <- rnLExpr usingExpr + ((stmts', binders, (maybeByExpr', thing)), fvs) <- + rnNormalStmtsAndFindUsedBinders (TransformStmtCtxt ctxt) stmts $ \unshadowed_bndrs -> do + (maybeByExpr', fv_maybeByExpr) <- rnMaybeLExpr maybeByExpr + (thing, fv_thing) <- thing_inside + + return ((maybeByExpr', thing), fv_maybeByExpr `plusFV` fv_thing) + + return ((TransformStmt (stmts', binders) usingExpr' maybeByExpr', thing), fv_usingExpr `plusFV` fvs) + where + rnMaybeLExpr Nothing = return (Nothing, emptyFVs) + rnMaybeLExpr (Just expr) = do + (expr', fv_expr) <- rnLExpr expr + return (Just expr', fv_expr) + +rnStmt ctxt (GroupStmt (stmts, _) groupByClause) thing_inside = do + checkIsTransformableListComp ctxt + + -- We must rename the using expression in the context before the transform is begun + groupByClauseAction <- + case groupByClause of + GroupByNothing usingExpr -> do + (usingExpr', fv_usingExpr) <- rnLExpr usingExpr + (return . return) (GroupByNothing usingExpr', fv_usingExpr) + GroupBySomething eitherUsingExpr byExpr -> do + (eitherUsingExpr', fv_eitherUsingExpr) <- + case eitherUsingExpr of + Right _ -> return (Right $ HsVar groupWithName, unitNameSet groupWithName) + Left usingExpr -> do + (usingExpr', fv_usingExpr) <- rnLExpr usingExpr + return (Left usingExpr', fv_usingExpr) + + return $ do + (byExpr', fv_byExpr) <- rnLExpr byExpr + return (GroupBySomething eitherUsingExpr' byExpr', fv_eitherUsingExpr `plusFV` fv_byExpr) + + -- We only use rnNormalStmtsAndFindUsedBinders to get unshadowed_bndrs, so + -- perhaps we could refactor this to use rnNormalStmts directly? + ((stmts', _, (groupByClause', usedBinderMap, thing)), fvs) <- + rnNormalStmtsAndFindUsedBinders (TransformStmtCtxt ctxt) stmts $ \unshadowed_bndrs -> do + (groupByClause', fv_groupByClause) <- groupByClauseAction + + unshadowed_bndrs' <- mapM newLocalName unshadowed_bndrs + let binderMap = zip unshadowed_bndrs unshadowed_bndrs' + + -- Bind the "thing" inside a context where we have REBOUND everything + -- bound by the statements before the group. This is necessary since after + -- the grouping the same identifiers actually have different meanings + -- i.e. they refer to lists not singletons! + (thing, fv_thing) <- bindLocalNames unshadowed_bndrs' thing_inside + + -- We remove entries from the binder map that are not used in the thing_inside. + -- We can then use that usage information to ensure that the free variables do + -- not contain the things we just bound, but do contain the things we need to + -- make those bindings (i.e. the corresponding non-listy variables) + + -- Note that we also retain those entries which have an old binder in our + -- own free variables (the using or by expression). This is because this map + -- is reused in the desugarer to create the type to bind from the statements + -- that occur before this one. If the binders we need are not in the map, they + -- will never get bound into our desugared expression and hence the simplifier + -- crashes as we refer to variables that don't exist! + let usedBinderMap = filter + (\(old_binder, new_binder) -> + (new_binder `elemNameSet` fv_thing) || + (old_binder `elemNameSet` fv_groupByClause)) binderMap + (usedOldBinders, usedNewBinders) = unzip usedBinderMap + real_fv_thing = (delListFromNameSet fv_thing usedNewBinders) `plusFV` (mkNameSet usedOldBinders) + + return ((groupByClause', usedBinderMap, thing), fv_groupByClause `plusFV` real_fv_thing) + + traceRn (text "rnStmt: implicitly rebound these used binders:" <+> ppr usedBinderMap) + return ((GroupStmt (stmts', usedBinderMap) groupByClause', thing), fvs) + rnStmt ctxt (ParStmt segs) thing_inside = do { parallel_list_comp <- doptM Opt_ParallelListComp ; checkM parallel_list_comp parStmtErr - ; orig_lcl_env <- getLocalRdrEnv - ; ((segs',thing), fvs) <- go orig_lcl_env [] segs + ; ((segs', thing), fvs) <- rnParallelStmts (ParStmtCtxt ctxt) segs thing_inside ; return ((ParStmt segs', thing), fvs) } + + +rnNormalStmtsAndFindUsedBinders :: HsStmtContext Name + -> [LStmt RdrName] + -> ([Name] -> RnM (thing, FreeVars)) + -> RnM (([LStmt Name], [Name], thing), FreeVars) +rnNormalStmtsAndFindUsedBinders ctxt stmts thing_inside = do + ((stmts', (used_bndrs, inner_thing)), fvs) <- rnNormalStmts ctxt stmts $ do + -- Find the Names that are bound by stmts that + -- by assumption we have just renamed + local_env <- getLocalRdrEnv + let + stmts_binders = collectLStmtsBinders stmts + bndrs = map (expectJust "rnStmt" + . lookupLocalRdrEnv local_env + . unLoc) stmts_binders + + -- If shadow, we'll look up (Unqual x) twice, getting + -- the second binding both times, which is the + -- one we want + unshadowed_bndrs = nub bndrs + + -- Typecheck the thing inside, passing on all + -- the Names bound before it for its information + (thing, fvs) <- thing_inside unshadowed_bndrs + + -- Figure out which of the bound names are used + -- after the statements we renamed + let used_bndrs = filter (`elemNameSet` fvs) bndrs + return ((used_bndrs, thing), fvs) + + -- Flatten the tuple returned by the above call a bit! + return ((stmts', used_bndrs, inner_thing), fvs) + + +rnParallelStmts ctxt segs thing_inside = do + orig_lcl_env <- getLocalRdrEnv + go orig_lcl_env [] segs + where + go orig_lcl_env bndrs [] = do + let (bndrs', dups) = removeDups cmpByOcc bndrs + inner_env = extendLocalRdrEnv orig_lcl_env bndrs' + + mappM dupErr dups + (thing, fvs) <- setLocalRdrEnv inner_env thing_inside + return (([], thing), fvs) + + go orig_lcl_env bndrs_so_far ((stmts, _) : segs) = do + ((stmts', bndrs, (segs', thing)), fvs) <- rnNormalStmtsAndFindUsedBinders ctxt stmts $ \new_bndrs -> do + -- Typecheck the thing inside, passing on all + -- the Names bound, but separately; revert the envt + setLocalRdrEnv orig_lcl_env $ do + go orig_lcl_env (new_bndrs ++ bndrs_so_far) segs + + let seg' = (stmts', bndrs) + return (((seg':segs'), thing), delListFromNameSet fvs bndrs) + + cmpByOcc n1 n2 = nameOccName n1 `compare` nameOccName n2 + dupErr vs = addErr (ptext SLIT("Duplicate binding in parallel list comprehension for:") + <+> quotes (ppr (head vs))) + + +checkIsTransformableListComp :: HsStmtContext Name -> RnM () +checkIsTransformableListComp ctxt = do + -- Ensure we are really within a list comprehension because otherwise the + -- desugarer will break when we come to operate on a parallel array + checkM (notParallelArray ctxt) transformStmtOutsideListCompErr + + -- Ensure the user has turned the correct flag on + transform_list_comp <- doptM Opt_TransformListComp + checkM transform_list_comp transformStmtErr where --- type ParSeg id = [([LStmt id], [id])] --- go :: NameSet -> [ParSeg RdrName] --- -> RnM (([ParSeg Name], thing), FreeVars) - - go orig_lcl_env bndrs [] - = do { let { (bndrs', dups) = removeDups cmpByOcc bndrs - ; inner_env = extendLocalRdrEnv orig_lcl_env bndrs' } - ; mappM dupErr dups - ; (thing, fvs) <- setLocalRdrEnv inner_env thing_inside - ; return (([], thing), fvs) } - - go orig_lcl_env bndrs_so_far ((stmts, _) : segs) - = do { ((stmts', (bndrs, segs', thing)), fvs) - <- rnNormalStmts par_ctxt stmts $ do - { -- Find the Names that are bound by stmts - lcl_env <- getLocalRdrEnv - ; let { rdr_bndrs = collectLStmtsBinders stmts - ; bndrs = map ( expectJust "rnStmt" - . lookupLocalRdrEnv lcl_env - . unLoc) rdr_bndrs - ; new_bndrs = nub bndrs ++ bndrs_so_far - -- The nub is because there might be shadowing - -- x <- e1; x <- e2 - -- So we'll look up (Unqual x) twice, getting - -- the second binding both times, which is the - } -- one we want - - -- Typecheck the thing inside, passing on all - -- the Names bound, but separately; revert the envt - ; ((segs', thing), fvs) <- setLocalRdrEnv orig_lcl_env $ - go orig_lcl_env new_bndrs segs - - -- Figure out which of the bound names are used - ; let used_bndrs = filter (`elemNameSet` fvs) bndrs - ; return ((used_bndrs, segs', thing), fvs) } - - ; let seg' = (stmts', bndrs) - ; return (((seg':segs'), thing), - delListFromNameSet fvs bndrs) } - - par_ctxt = ParStmtCtxt ctxt - - cmpByOcc n1 n2 = nameOccName n1 `compare` nameOccName n2 - dupErr vs = addErr (ptext SLIT("Duplicate binding in parallel list comprehension for:") - <+> quotes (ppr (head vs))) + notParallelArray PArrComp = False + notParallelArray _ = True + \end{code} @@ -833,7 +939,13 @@ rn_rec_stmt_lhs fix_env (L loc (RecStmt stmts _ _ _ _)) -- Flatten Rec inside Re rn_rec_stmt_lhs _ stmt@(L _ (ParStmt _)) -- Syntactically illegal in mdo = pprPanic "rn_rec_stmt" (ppr stmt) - + +rn_rec_stmt_lhs _ stmt@(L _ (TransformStmt _ _ _)) -- Syntactically illegal in mdo + = pprPanic "rn_rec_stmt" (ppr stmt) + +rn_rec_stmt_lhs _ stmt@(L _ (GroupStmt _ _)) -- Syntactically illegal in mdo + = pprPanic "rn_rec_stmt" (ppr stmt) + rn_rec_stmts_lhs :: UniqFM (Located Fixity) -- mini fixity env for the names we're about to bind -- these fixities need to be brought into scope with the names -> [LStmt RdrName] @@ -890,6 +1002,12 @@ rn_rec_stmt all_bndrs stmt@(L loc (RecStmt stmts _ _ _ _)) _ rn_rec_stmt all_bndrs stmt@(L _ (ParStmt _)) _ -- Syntactically illegal in mdo = pprPanic "rn_rec_stmt: ParStmt" (ppr stmt) +rn_rec_stmt all_bndrs stmt@(L _ (TransformStmt _ _ _)) _ -- Syntactically illegal in mdo + = pprPanic "rn_rec_stmt: TransformStmt" (ppr stmt) + +rn_rec_stmt all_bndrs stmt@(L _ (GroupStmt _ _)) _ -- Syntactically illegal in mdo + = pprPanic "rn_rec_stmt: GroupStmt" (ppr stmt) + rn_rec_stmts :: [Name] -> [(LStmtLR Name RdrName, FreeVars)] -> RnM [Segment (LStmt Name)] rn_rec_stmts bndrs stmts = mappM (uncurry (rn_rec_stmt bndrs)) stmts `thenM` \ segs_s -> returnM (concat segs_s) @@ -1027,8 +1145,12 @@ patSynErr e = do { addErr (sep [ptext SLIT("Pattern syntax in expression context nest 4 (ppr e)]) ; return (EWildPat, emptyFVs) } + parStmtErr = addErr (ptext SLIT("Illegal parallel list comprehension: use -XParallelListComp")) +transformStmtErr = addErr (ptext SLIT("Illegal transform or grouping list comprehension: use -XTransformListComp")) +transformStmtOutsideListCompErr = addErr (ptext SLIT("Currently you may only use transform or grouping comprehensions within list comprehensions, not parallel array comprehensions")) + badIpBinds what binds = hang (ptext SLIT("Implicit-parameter bindings illegal in") <+> what) 2 (ppr binds)