import Data.List
import Util ( isSingleton )
import ListSetOps ( removeDups )
-import Maybes ( expectJust )
import Outputable
import SrcLoc
import FastString
methodNamesStmt (RecStmt { recS_stmts = stmts }) = methodNamesStmts stmts `addOneFV` loopAName
methodNamesStmt (LetStmt _) = emptyFVs
methodNamesStmt (ParStmt _) = emptyFVs
-methodNamesStmt (TransformStmt _ _ _) = emptyFVs
-methodNamesStmt (GroupStmt _ _) = emptyFVs
+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}
rnStmts :: HsStmtContext Name -> [LStmt RdrName]
-> RnM (thing, FreeVars)
-> RnM (([LStmt Name], thing), FreeVars)
+-- Variables bound by the Stmts, and mentioned in thing_inside,
+-- do not appear in the result FreeVars
-rnStmts (MDoExpr _) = rnMDoStmts
-rnStmts ctxt = rnNormalStmts ctxt
+rnStmts (MDoExpr _) stmts thing_inside = rnMDoStmts stmts thing_inside
+rnStmts ctxt stmts thing_inside = rnNormalStmts ctxt stmts (\ _ -> thing_inside)
rnNormalStmts :: HsStmtContext Name -> [LStmt RdrName]
- -> RnM (thing, FreeVars)
+ -> ([Name] -> RnM (thing, FreeVars))
-> RnM (([LStmt Name], thing), FreeVars)
+-- Variables bound by the Stmts, and mentioned in thing_inside,
+-- do not appear in the result FreeVars
+--
+-- Renaming a single RecStmt can give a sequence of smaller Stmts
+
rnNormalStmts _ [] thing_inside
- = do { (thing, fvs) <- thing_inside
- ; return (([],thing), fvs) }
+ = do { (res, fvs) <- thing_inside []
+ ; return (([], res), fvs) }
rnNormalStmts ctxt (stmt@(L loc _) : stmts) thing_inside
= do { ((stmts1, (stmts2, thing)), fvs)
- <- setSrcSpan loc $
- rnStmt ctxt stmt $
- rnNormalStmts ctxt stmts thing_inside
+ <- setSrcSpan loc $
+ rnStmt ctxt stmt $ \ bndrs1 ->
+ rnNormalStmts ctxt stmts $ \ bndrs2 ->
+ thing_inside (bndrs1 ++ bndrs2)
; return (((stmts1 ++ stmts2), thing), fvs) }
rnStmt :: HsStmtContext Name -> LStmt RdrName
- -> RnM (thing, FreeVars)
+ -> ([Name] -> RnM (thing, FreeVars))
-> RnM (([LStmt Name], thing), FreeVars)
+-- Variables bound by the Stmt, and mentioned in thing_inside,
+-- do not appear in the result FreeVars
rnStmt _ (L loc (ExprStmt expr _ _)) thing_inside
= do { (expr', fv_expr) <- rnLExpr expr
; (then_op, fvs1) <- lookupSyntaxName thenMName
- ; (thing, fvs2) <- thing_inside
+ ; (thing, fvs2) <- thing_inside []
; return (([L loc (ExprStmt expr' then_op placeHolderType)], thing),
fv_expr `plusFV` fvs1 `plusFV` fvs2) }
; (bind_op, fvs1) <- lookupSyntaxName bindMName
; (fail_op, fvs2) <- lookupSyntaxName failMName
; rnPat (StmtCtxt ctxt) pat $ \ pat' -> do
- { (thing, fvs3) <- thing_inside
+ { (thing, fvs3) <- thing_inside (collectPatBinders pat')
; return (([L loc (BindStmt pat' expr' bind_op fail_op)], thing),
fv_expr `plusFV` fvs1 `plusFV` fvs2 `plusFV` fvs3) }}
-- fv_expr shouldn't really be filtered by the rnPatsAndThen
rnStmt ctxt (L loc (LetStmt binds)) thing_inside
= do { checkLetStmt ctxt binds
; rnLocalBindsAndThen binds $ \binds' -> do
- { (thing, fvs) <- thing_inside
+ { (thing, fvs) <- thing_inside (collectLocalBinders binds')
; return (([L loc (LetStmt binds')], thing), fvs) } }
rnStmt ctxt (L _ (RecStmt { recS_stmts = rec_stmts })) thing_inside
-- context.)
; rn_rec_stmts_and_then rec_stmts $ \ segs -> do
- { (thing, fvs_later) <- thing_inside
+ { let bndrs = nameSetToList $ foldr (unionNameSets . (\(ds,_,_,_) -> ds))
+ emptyNameSet segs
+ ; (thing, fvs_later) <- thing_inside bndrs
; (return_op, fvs1) <- lookupSyntaxName returnMName
; (mfix_op, fvs2) <- lookupSyntaxName mfixName
; (bind_op, fvs3) <- lookupSyntaxName bindMName
; ((segs', thing), fvs) <- rnParallelStmts (ParStmtCtxt ctxt) segs thing_inside
; return (([L loc (ParStmt segs')], thing), fvs) }
-rnStmt ctxt (L loc (TransformStmt (stmts, _) usingExpr maybeByExpr)) thing_inside = do
- checkTransformStmt 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)
+rnStmt ctxt (L loc (TransformStmt stmts _ using by)) thing_inside
+ = do { checkTransformStmt ctxt
- return (([L loc (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)
+ ; (using', fvs1) <- rnLExpr using
+
+ ; ((stmts', (by', used_bndrs, thing)), fvs2)
+ <- rnNormalStmts (TransformStmtCtxt ctxt) stmts $ \ bndrs ->
+ do { (by', fvs_by) <- case by of
+ Nothing -> return (Nothing, emptyFVs)
+ Just e -> do { (e', fvs) <- rnLExpr e; return (Just e', fvs) }
+ ; (thing, fvs_thing) <- thing_inside bndrs
+ ; let fvs = fvs_by `plusFV` fvs_thing
+ used_bndrs = filter (`elemNameSet` fvs_thing) bndrs
+ ; return ((by', used_bndrs, thing), fvs) }
+
+ ; return (([L loc (TransformStmt stmts' used_bndrs using' by')], thing),
+ fvs1 `plusFV` fvs2) }
-rnStmt ctxt (L loc (GroupStmt (stmts, _) groupByClause)) thing_inside = do
- checkTransformStmt 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)
+rnStmt ctxt (L loc (GroupStmt stmts _ by using)) thing_inside
+ = do { checkTransformStmt ctxt
- -- 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 (([L loc (GroupStmt (stmts', usedBinderMap) groupByClause')], 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 :: HsStmtContext Name -> [([LStmt RdrName], [RdrName])]
- -> RnM (thing, FreeVars)
- -> RnM (([([LStmt Name], [Name])], thing), FreeVars)
-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 = extendLocalRdrEnvList orig_lcl_env bndrs'
-
- mapM_ 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:")
+ -- Rename the 'using' expression in the context before the transform is begun
+ ; (using', fvs1) <- case using of
+ Left e -> do { (e', fvs) <- rnLExpr e; return (Left e', fvs) }
+ Right _ -> do { (e', fvs) <- lookupSyntaxName groupWithName
+ ; return (Right e', fvs) }
+
+ -- Rename the stmts and the 'by' expression
+ -- Keep track of the variables mentioned in the 'by' expression
+ ; ((stmts', (by', used_bndrs, thing)), fvs2)
+ <- rnNormalStmts (TransformStmtCtxt ctxt) stmts $ \ bndrs ->
+ do { (by', fvs_by) <- mapMaybeFvRn rnLExpr by
+ ; (thing, fvs_thing) <- thing_inside bndrs
+ ; let fvs = fvs_by `plusFV` fvs_thing
+ used_bndrs = filter (`elemNameSet` fvs) bndrs
+ ; return ((by', used_bndrs, thing), fvs) }
+
+ ; let all_fvs = fvs1 `plusFV` fvs2
+ bndr_map = used_bndrs `zip` used_bndrs
+
+ ; traceRn (text "rnStmt: implicitly rebound these used binders:" <+> ppr bndr_map)
+ ; return (([L loc (GroupStmt stmts' bndr_map by' using')], thing), all_fvs) }
+
+
+type ParSeg id = ([LStmt id], [id]) -- The Names are bound by the Stmts
+
+rnParallelStmts :: forall thing. HsStmtContext Name
+ -> [ParSeg RdrName]
+ -> ([Name] -> RnM (thing, FreeVars))
+ -> RnM (([ParSeg Name], thing), FreeVars)
+-- Note [Renaming parallel Stmts]
+rnParallelStmts ctxt segs thing_inside
+ = do { orig_lcl_env <- getLocalRdrEnv
+ ; rn_segs orig_lcl_env [] segs }
+ where
+ rn_segs :: LocalRdrEnv
+ -> [Name] -> [ParSeg RdrName]
+ -> RnM (([ParSeg Name], thing), FreeVars)
+ rn_segs _ bndrs_so_far []
+ = do { let (bndrs', dups) = removeDups cmpByOcc bndrs_so_far
+ ; mapM_ dupErr dups
+ ; (thing, fvs) <- bindLocalNames bndrs' (thing_inside bndrs')
+ ; return (([], thing), fvs) }
+
+ rn_segs env bndrs_so_far ((stmts,_) : segs)
+ = do { ((stmts', (used_bndrs, segs', thing)), fvs)
+ <- rnNormalStmts ctxt stmts $ \ bndrs ->
+ setLocalRdrEnv env $ do
+ { ((segs', thing), fvs) <- rn_segs env (bndrs ++ bndrs_so_far) segs
+ ; let used_bndrs = filter (`elemNameSet` fvs) bndrs
+ ; return ((used_bndrs, segs', thing), fvs) }
+
+ ; let seg' = (stmts', used_bndrs)
+ ; return ((seg':segs', thing), fvs) }
+
+ cmpByOcc n1 n2 = nameOccName n1 `compare` nameOccName n2
+ dupErr vs = addErr (ptext (sLit "Duplicate binding in parallel list comprehension for:")
<+> quotes (ppr (head vs)))
\end{code}
+Note [Renaming parallel Stmts]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Renaming parallel statements is painful. Given, say
+ [ a+c | a <- as, bs <- bss
+ | c <- bs, a <- ds ]
+Note that
+ (a) In order to report "Defined by not used" about 'bs', we must rename
+ each group of Stmts with a thing_inside whose FreeVars include at least {a,c}
+
+ (b) We want to report that 'a' is illegally bound in both branches
+
+ (c) The 'bs' in the second group must obviously not be captured by
+ the binding in the first group
+
+To satisfy (a) we nest the segements.
+To satisfy (b) we check for duplicates just before thing_inside.
+To satisfy (c) we reset the LocalRdrEnv each time.
%************************************************************************
%* *
; new_lhs_and_fv <- rn_rec_stmts_lhs fix_env s
-- ...bring them and their fixities into scope
- ; let bound_names = map unLoc $ collectLStmtsBinders (map fst new_lhs_and_fv)
+ ; let bound_names = collectLStmtsBinders (map fst new_lhs_and_fv)
; bindLocalNamesFV_WithFixities bound_names fix_env $ do
-- (C) do the right-hand-sides and thing-inside
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
+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
+rn_rec_stmt_lhs _ stmt@(L _ (GroupStmt {})) -- Syntactically illegal in mdo
= pprPanic "rn_rec_stmt" (ppr stmt)
rn_rec_stmt_lhs _ (L _ (LetStmt EmptyLocalBinds))
-> [LStmt RdrName]
-> RnM [(LStmtLR Name RdrName, FreeVars)]
rn_rec_stmts_lhs fix_env stmts
- = do { let boundNames = collectLStmtsBinders stmts
+ = do { ls <- concatMapM (rn_rec_stmt_lhs fix_env) stmts
+ ; let boundNames = collectLStmtsBinders (map fst ls)
-- First do error checking: we need to check for dups here because we
-- don't bind all of the variables from the Stmt at once
-- with bindLocatedLocals.
- ; checkDupRdrNames boundNames
- ; ls <- mapM (rn_rec_stmt_lhs fix_env) stmts
- ; return (concat ls) }
+ ; checkDupNames boundNames
+ ; return ls }
-- right-hand-sides
projects / ghc-hetmet.git / blobdiff