% % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998 % \section[RnExpr]{Renaming of expressions} Basically dependency analysis. Handles @Match@, @GRHSs@, @HsExpr@, and @Qualifier@ datatypes. In general, all of these functions return a renamed thing, and a set of free variables. \begin{code} {-# LANGUAGE CPP, ScopedTypeVariables #-} module RnExpr ( rnLExpr, rnExpr, rnStmts ) where #include "HsVersions.h" import {-# SOURCE #-} TcSplice( runQuasiQuoteExpr ) import RnBinds ( rnLocalBindsAndThen, rnLocalValBindsLHS, rnLocalValBindsRHS, rnMatchGroup, rnGRHS, makeMiniFixityEnv) import HsSyn import TcRnMonad import Module ( getModule ) import RnEnv import RnSplice ( rnBracket, rnSpliceExpr, checkThLocalName ) import RnTypes import RnPat import DynFlags import BasicTypes ( FixityDirection(..) ) import PrelNames import Name import NameSet import RdrName import UniqSet import Data.List import Util import ListSetOps ( removeDups ) import ErrUtils import Outputable import SrcLoc import FastString import Control.Monad import TysWiredIn ( nilDataConName ) \end{code} %************************************************************************ %* * \subsubsection{Expressions} %* * %************************************************************************ \begin{code} rnExprs :: [LHsExpr RdrName] -> RnM ([LHsExpr Name], FreeVars) rnExprs ls = rnExprs' ls emptyUniqSet where rnExprs' [] acc = return ([], acc) rnExprs' (expr:exprs) acc = do { (expr', fvExpr) <- rnLExpr expr -- Now we do a "seq" on the free vars because typically it's small -- or empty, especially in very long lists of constants ; let acc' = acc `plusFV` fvExpr ; (exprs', fvExprs) <- acc' `seq` rnExprs' exprs acc' ; return (expr':exprs', fvExprs) } \end{code} Variables. We look up the variable and return the resulting name. \begin{code} rnLExpr :: LHsExpr RdrName -> RnM (LHsExpr Name, FreeVars) rnLExpr = wrapLocFstM rnExpr rnExpr :: HsExpr RdrName -> RnM (HsExpr Name, FreeVars) finishHsVar :: Name -> RnM (HsExpr Name, FreeVars) -- Separated from rnExpr because it's also used -- when renaming infix expressions -- See Note [Adding the implicit parameter to 'assert'] finishHsVar name = do { this_mod <- getModule ; when (nameIsLocalOrFrom this_mod name) $ checkThLocalName name ; ignore_asserts <- goptM Opt_IgnoreAsserts ; if ignore_asserts || not (name `hasKey` assertIdKey) then return (HsVar name, unitFV name) else do { e <- mkAssertErrorExpr ; return (e, unitFV name) } } rnExpr (HsVar v) = do { mb_name <- lookupOccRn_maybe v ; case mb_name of { Nothing -> do { opt_TypeHoles <- woptM Opt_WarnTypedHoles ; if opt_TypeHoles && startsWithUnderscore (rdrNameOcc v) then return (HsUnboundVar v, emptyFVs) else do { n <- reportUnboundName v; finishHsVar n } } ; Just name | name == nilDataConName -- Treat [] as an ExplicitList, so that -- OverloadedLists works correctly -> rnExpr (ExplicitList placeHolderType Nothing []) | otherwise -> finishHsVar name }} rnExpr (HsIPVar v) = return (HsIPVar v, emptyFVs) rnExpr (HsLit lit@(HsString s)) = do { opt_OverloadedStrings <- xoptM Opt_OverloadedStrings ; if opt_OverloadedStrings then rnExpr (HsOverLit (mkHsIsString s placeHolderType)) else do { ; rnLit lit ; return (HsLit lit, emptyFVs) } } rnExpr (HsLit lit) = do { rnLit lit ; return (HsLit lit, emptyFVs) } rnExpr (HsOverLit lit) = do { (lit', fvs) <- rnOverLit lit ; return (HsOverLit lit', fvs) } rnExpr (HsApp fun arg) = do { (fun',fvFun) <- rnLExpr fun ; (arg',fvArg) <- rnLExpr arg ; return (HsApp fun' arg', fvFun `plusFV` fvArg) } rnExpr (OpApp e1 (L op_loc (HsVar op_rdr)) _ e2) = do { (e1', fv_e1) <- rnLExpr e1 ; (e2', fv_e2) <- rnLExpr e2 ; op_name <- setSrcSpan op_loc (lookupOccRn op_rdr) ; (op', fv_op) <- finishHsVar op_name -- NB: op' is usually just a variable, but might be -- an applicatoin (assert "Foo.hs:47") -- Deal with fixity -- When renaming code synthesised from "deriving" declarations -- we used to avoid fixity stuff, but we can't easily tell any -- more, so I've removed the test. Adding HsPars in TcGenDeriv -- should prevent bad things happening. ; fixity <- lookupFixityRn op_name ; final_e <- mkOpAppRn e1' (L op_loc op') fixity e2' ; return (final_e, fv_e1 `plusFV` fv_op `plusFV` fv_e2) } rnExpr (OpApp _ other_op _ _) = failWith (vcat [ hang (ptext (sLit "Infix application with a non-variable operator:")) 2 (ppr other_op) , ptext (sLit "(Probably resulting from a Template Haskell splice)") ]) rnExpr (NegApp e _) = do { (e', fv_e) <- rnLExpr e ; (neg_name, fv_neg) <- lookupSyntaxName negateName ; final_e <- mkNegAppRn e' neg_name ; return (final_e, fv_e `plusFV` fv_neg) } ------------------------------------------ -- Template Haskell extensions -- Don't ifdef-GHCI them because we want to fail gracefully -- (not with an rnExpr crash) in a stage-1 compiler. rnExpr e@(HsBracket br_body) = rnBracket e br_body rnExpr (HsSpliceE is_typed splice) = rnSpliceExpr is_typed splice rnExpr (HsQuasiQuoteE qq) = do { lexpr' <- runQuasiQuoteExpr qq -- Wrap the result of the quasi-quoter in parens so that we don't -- lose the outermost location set by runQuasiQuote (#7918) ; rnExpr (HsPar lexpr') } --------------------------------------------- -- Sections -- See Note [Parsing sections] in Parser.y.pp rnExpr (HsPar (L loc (section@(SectionL {})))) = do { (section', fvs) <- rnSection section ; return (HsPar (L loc section'), fvs) } rnExpr (HsPar (L loc (section@(SectionR {})))) = do { (section', fvs) <- rnSection section ; return (HsPar (L loc section'), fvs) } rnExpr (HsPar e) = do { (e', fvs_e) <- rnLExpr e ; return (HsPar e', fvs_e) } rnExpr expr@(SectionL {}) = do { addErr (sectionErr expr); rnSection expr } rnExpr expr@(SectionR {}) = do { addErr (sectionErr expr); rnSection expr } --------------------------------------------- rnExpr (HsCoreAnn ann expr) = do { (expr', fvs_expr) <- rnLExpr expr ; return (HsCoreAnn ann expr', fvs_expr) } rnExpr (HsSCC lbl expr) = do { (expr', fvs_expr) <- rnLExpr expr ; return (HsSCC lbl expr', fvs_expr) } rnExpr (HsTickPragma info expr) = do { (expr', fvs_expr) <- rnLExpr expr ; return (HsTickPragma info expr', fvs_expr) } rnExpr (HsLam matches) = do { (matches', fvMatch) <- rnMatchGroup LambdaExpr rnLExpr matches ; return (HsLam matches', fvMatch) } rnExpr (HsLamCase _arg matches) = do { (matches', fvs_ms) <- rnMatchGroup CaseAlt rnLExpr matches -- ; return (HsLamCase arg matches', fvs_ms) } ; return (HsLamCase placeHolderType matches', fvs_ms) } rnExpr (HsCase expr matches) = do { (new_expr, e_fvs) <- rnLExpr expr ; (new_matches, ms_fvs) <- rnMatchGroup CaseAlt rnLExpr matches ; return (HsCase new_expr new_matches, e_fvs `plusFV` ms_fvs) } rnExpr (HsLet binds expr) = rnLocalBindsAndThen binds $ \binds' -> do { (expr',fvExpr) <- rnLExpr expr ; return (HsLet binds' expr', fvExpr) } rnExpr (HsDo do_or_lc stmts _) = do { ((stmts', _), fvs) <- rnStmts do_or_lc rnLExpr stmts (\ _ -> return ((), emptyFVs)) ; return ( HsDo do_or_lc stmts' placeHolderType, fvs ) } rnExpr (ExplicitList _ _ exps) = do { opt_OverloadedLists <- xoptM Opt_OverloadedLists ; (exps', fvs) <- rnExprs exps ; if opt_OverloadedLists then do { ; (from_list_n_name, fvs') <- lookupSyntaxName fromListNName ; return (ExplicitList placeHolderType (Just from_list_n_name) exps' , fvs `plusFV` fvs') } else return (ExplicitList placeHolderType Nothing exps', fvs) } rnExpr (ExplicitPArr _ exps) = do { (exps', fvs) <- rnExprs exps ; return (ExplicitPArr placeHolderType exps', fvs) } rnExpr (ExplicitTuple tup_args boxity) = do { checkTupleSection tup_args ; checkTupSize (length tup_args) ; (tup_args', fvs) <- mapAndUnzipM rnTupArg tup_args ; return (ExplicitTuple tup_args' boxity, plusFVs fvs) } where rnTupArg (Present e) = do { (e',fvs) <- rnLExpr e; return (Present e', fvs) } rnTupArg (Missing _) = return (Missing placeHolderType, emptyFVs) rnExpr (RecordCon con_id _ rbinds) = do { conname <- lookupLocatedOccRn con_id ; (rbinds', fvRbinds) <- rnHsRecBinds (HsRecFieldCon (unLoc conname)) rbinds ; return (RecordCon conname noPostTcExpr rbinds', fvRbinds `addOneFV` unLoc conname) } rnExpr (RecordUpd expr rbinds _ _ _) = do { (expr', fvExpr) <- rnLExpr expr ; (rbinds', fvRbinds) <- rnHsRecBinds HsRecFieldUpd rbinds ; return (RecordUpd expr' rbinds' [] [] [], fvExpr `plusFV` fvRbinds) } rnExpr (ExprWithTySig expr pty) = do { (pty', fvTy) <- rnLHsType ExprWithTySigCtx pty ; (expr', fvExpr) <- bindSigTyVarsFV (hsExplicitTvs pty') $ rnLExpr expr ; return (ExprWithTySig expr' pty', fvExpr `plusFV` fvTy) } rnExpr (HsIf _ p b1 b2) = do { (p', fvP) <- rnLExpr p ; (b1', fvB1) <- rnLExpr b1 ; (b2', fvB2) <- rnLExpr b2 ; (mb_ite, fvITE) <- lookupIfThenElse ; return (HsIf mb_ite p' b1' b2', plusFVs [fvITE, fvP, fvB1, fvB2]) } rnExpr (HsMultiIf _ty alts) = do { (alts', fvs) <- mapFvRn (rnGRHS IfAlt rnLExpr) alts -- ; return (HsMultiIf ty alts', fvs) } ; return (HsMultiIf placeHolderType alts', fvs) } rnExpr (HsType a) = do { (t, fvT) <- rnLHsType HsTypeCtx a ; return (HsType t, fvT) } rnExpr (ArithSeq _ _ seq) = do { opt_OverloadedLists <- xoptM Opt_OverloadedLists ; (new_seq, fvs) <- rnArithSeq seq ; if opt_OverloadedLists then do { ; (from_list_name, fvs') <- lookupSyntaxName fromListName ; return (ArithSeq noPostTcExpr (Just from_list_name) new_seq, fvs `plusFV` fvs') } else return (ArithSeq noPostTcExpr Nothing new_seq, fvs) } rnExpr (PArrSeq _ seq) = do { (new_seq, fvs) <- rnArithSeq seq ; return (PArrSeq noPostTcExpr new_seq, fvs) } \end{code} These three are pattern syntax appearing in expressions. Since all the symbols are reservedops we can simply reject them. We return a (bogus) EWildPat in each case. \begin{code} rnExpr e@EWildPat = do { holes <- woptM Opt_WarnTypedHoles ; if holes then return (hsHoleExpr, emptyFVs) else patSynErr e } rnExpr e@(EAsPat {}) = patSynErr e rnExpr e@(EViewPat {}) = patSynErr e rnExpr e@(ELazyPat {}) = patSynErr e \end{code} %************************************************************************ %* * Arrow notation %* * %************************************************************************ \begin{code} rnExpr (HsProc pat body) = newArrowScope $ rnPat ProcExpr pat $ \ pat' -> do { (body',fvBody) <- rnCmdTop body ; return (HsProc pat' body', fvBody) } -- Ideally, these would be done in parsing, but to keep parsing simple, we do it here. rnExpr e@(HsArrApp {}) = arrowFail e rnExpr e@(HsArrForm {}) = arrowFail e rnExpr other = pprPanic "rnExpr: unexpected expression" (ppr other) -- HsWrap hsHoleExpr :: HsExpr Name hsHoleExpr = HsUnboundVar (mkRdrUnqual (mkVarOcc "_")) arrowFail :: HsExpr RdrName -> RnM (HsExpr Name, FreeVars) arrowFail e = do { addErr (vcat [ ptext (sLit "Arrow command found where an expression was expected:") , nest 2 (ppr e) ]) -- Return a place-holder hole, so that we can carry on -- to report other errors ; return (hsHoleExpr, emptyFVs) } ---------------------- -- See Note [Parsing sections] in Parser.y.pp rnSection :: HsExpr RdrName -> RnM (HsExpr Name, FreeVars) rnSection section@(SectionR op expr) = do { (op', fvs_op) <- rnLExpr op ; (expr', fvs_expr) <- rnLExpr expr ; checkSectionPrec InfixR section op' expr' ; return (SectionR op' expr', fvs_op `plusFV` fvs_expr) } rnSection section@(SectionL expr op) = do { (expr', fvs_expr) <- rnLExpr expr ; (op', fvs_op) <- rnLExpr op ; checkSectionPrec InfixL section op' expr' ; return (SectionL expr' op', fvs_op `plusFV` fvs_expr) } rnSection other = pprPanic "rnSection" (ppr other) \end{code} %************************************************************************ %* * Records %* * %************************************************************************ \begin{code} rnHsRecBinds :: HsRecFieldContext -> HsRecordBinds RdrName -> RnM (HsRecordBinds Name, FreeVars) rnHsRecBinds ctxt rec_binds@(HsRecFields { rec_dotdot = dd }) = do { (flds, fvs) <- rnHsRecFields ctxt HsVar rec_binds ; (flds', fvss) <- mapAndUnzipM rn_field flds ; return (HsRecFields { rec_flds = flds', rec_dotdot = dd }, fvs `plusFV` plusFVs fvss) } where rn_field fld = do { (arg', fvs) <- rnLExpr (hsRecFieldArg fld) ; return (fld { hsRecFieldArg = arg' }, fvs) } \end{code} %************************************************************************ %* * Arrow commands %* * %************************************************************************ \begin{code} rnCmdArgs :: [LHsCmdTop RdrName] -> RnM ([LHsCmdTop Name], FreeVars) rnCmdArgs [] = return ([], emptyFVs) rnCmdArgs (arg:args) = do { (arg',fvArg) <- rnCmdTop arg ; (args',fvArgs) <- rnCmdArgs args ; return (arg':args', fvArg `plusFV` fvArgs) } rnCmdTop :: LHsCmdTop RdrName -> RnM (LHsCmdTop Name, FreeVars) rnCmdTop = wrapLocFstM rnCmdTop' where rnCmdTop' (HsCmdTop cmd _ _ _) = do { (cmd', fvCmd) <- rnLCmd cmd ; let cmd_names = [arrAName, composeAName, firstAName] ++ nameSetToList (methodNamesCmd (unLoc cmd')) -- Generate the rebindable syntax for the monad ; (cmd_names', cmd_fvs) <- lookupSyntaxNames cmd_names ; return (HsCmdTop cmd' placeHolderType placeHolderType (cmd_names `zip` cmd_names'), fvCmd `plusFV` cmd_fvs) } rnLCmd :: LHsCmd RdrName -> RnM (LHsCmd Name, FreeVars) rnLCmd = wrapLocFstM rnCmd rnCmd :: HsCmd RdrName -> RnM (HsCmd Name, FreeVars) rnCmd (HsCmdArrApp arrow arg _ ho rtl) = do { (arrow',fvArrow) <- select_arrow_scope (rnLExpr arrow) ; (arg',fvArg) <- rnLExpr arg ; return (HsCmdArrApp arrow' arg' placeHolderType ho rtl, fvArrow `plusFV` fvArg) } where select_arrow_scope tc = case ho of HsHigherOrderApp -> tc HsFirstOrderApp -> escapeArrowScope tc -- See Note [Escaping the arrow scope] in TcRnTypes -- Before renaming 'arrow', use the environment of the enclosing -- proc for the (-<) case. -- Local bindings, inside the enclosing proc, are not in scope -- inside 'arrow'. In the higher-order case (-<<), they are. -- infix form rnCmd (HsCmdArrForm op (Just _) [arg1, arg2]) = do { (op',fv_op) <- escapeArrowScope (rnLExpr op) ; let L _ (HsVar op_name) = op' ; (arg1',fv_arg1) <- rnCmdTop arg1 ; (arg2',fv_arg2) <- rnCmdTop arg2 -- Deal with fixity ; fixity <- lookupFixityRn op_name ; final_e <- mkOpFormRn arg1' op' fixity arg2' ; return (final_e, fv_arg1 `plusFV` fv_op `plusFV` fv_arg2) } rnCmd (HsCmdArrForm op fixity cmds) = do { (op',fvOp) <- escapeArrowScope (rnLExpr op) ; (cmds',fvCmds) <- rnCmdArgs cmds ; return (HsCmdArrForm op' fixity cmds', fvOp `plusFV` fvCmds) } rnCmd (HsCmdApp fun arg) = do { (fun',fvFun) <- rnLCmd fun ; (arg',fvArg) <- rnLExpr arg ; return (HsCmdApp fun' arg', fvFun `plusFV` fvArg) } rnCmd (HsCmdLam matches) = do { (matches', fvMatch) <- rnMatchGroup LambdaExpr rnLCmd matches ; return (HsCmdLam matches', fvMatch) } rnCmd (HsCmdPar e) = do { (e', fvs_e) <- rnLCmd e ; return (HsCmdPar e', fvs_e) } rnCmd (HsCmdCase expr matches) = do { (new_expr, e_fvs) <- rnLExpr expr ; (new_matches, ms_fvs) <- rnMatchGroup CaseAlt rnLCmd matches ; return (HsCmdCase new_expr new_matches, e_fvs `plusFV` ms_fvs) } rnCmd (HsCmdIf _ p b1 b2) = do { (p', fvP) <- rnLExpr p ; (b1', fvB1) <- rnLCmd b1 ; (b2', fvB2) <- rnLCmd b2 ; (mb_ite, fvITE) <- lookupIfThenElse ; return (HsCmdIf mb_ite p' b1' b2', plusFVs [fvITE, fvP, fvB1, fvB2]) } rnCmd (HsCmdLet binds cmd) = rnLocalBindsAndThen binds $ \ binds' -> do { (cmd',fvExpr) <- rnLCmd cmd ; return (HsCmdLet binds' cmd', fvExpr) } rnCmd (HsCmdDo stmts _) = do { ((stmts', _), fvs) <- rnStmts ArrowExpr rnLCmd stmts (\ _ -> return ((), emptyFVs)) ; return ( HsCmdDo stmts' placeHolderType, fvs ) } rnCmd cmd@(HsCmdCast {}) = pprPanic "rnCmd" (ppr cmd) --------------------------------------------------- type CmdNeeds = FreeVars -- Only inhabitants are -- appAName, choiceAName, loopAName -- find what methods the Cmd needs (loop, choice, apply) methodNamesLCmd :: LHsCmd Name -> CmdNeeds methodNamesLCmd = methodNamesCmd . unLoc methodNamesCmd :: HsCmd Name -> CmdNeeds methodNamesCmd (HsCmdArrApp _arrow _arg _ HsFirstOrderApp _rtl) = emptyFVs methodNamesCmd (HsCmdArrApp _arrow _arg _ HsHigherOrderApp _rtl) = unitFV appAName methodNamesCmd (HsCmdArrForm {}) = emptyFVs methodNamesCmd (HsCmdCast _ cmd) = methodNamesCmd cmd methodNamesCmd (HsCmdPar c) = methodNamesLCmd c methodNamesCmd (HsCmdIf _ _ c1 c2) = methodNamesLCmd c1 `plusFV` methodNamesLCmd c2 `addOneFV` choiceAName methodNamesCmd (HsCmdLet _ c) = methodNamesLCmd c methodNamesCmd (HsCmdDo stmts _) = methodNamesStmts stmts methodNamesCmd (HsCmdApp c _) = methodNamesLCmd c methodNamesCmd (HsCmdLam match) = methodNamesMatch match methodNamesCmd (HsCmdCase _ matches) = methodNamesMatch matches `addOneFV` choiceAName --methodNamesCmd _ = emptyFVs -- Other forms can't occur in commands, but it's not convenient -- to error here so we just do what's convenient. -- The type checker will complain later --------------------------------------------------- methodNamesMatch :: MatchGroup Name (LHsCmd Name) -> FreeVars methodNamesMatch (MG { mg_alts = ms }) = plusFVs (map do_one ms) where do_one (L _ (Match _ _ grhss)) = methodNamesGRHSs grhss ------------------------------------------------- -- gaw 2004 methodNamesGRHSs :: GRHSs Name (LHsCmd Name) -> FreeVars methodNamesGRHSs (GRHSs grhss _) = plusFVs (map methodNamesGRHS grhss) ------------------------------------------------- methodNamesGRHS :: Located (GRHS Name (LHsCmd Name)) -> CmdNeeds methodNamesGRHS (L _ (GRHS _ rhs)) = methodNamesLCmd rhs --------------------------------------------------- methodNamesStmts :: [Located (StmtLR Name Name (LHsCmd Name))] -> FreeVars methodNamesStmts stmts = plusFVs (map methodNamesLStmt stmts) --------------------------------------------------- methodNamesLStmt :: Located (StmtLR Name Name (LHsCmd Name)) -> FreeVars methodNamesLStmt = methodNamesStmt . unLoc methodNamesStmt :: StmtLR Name Name (LHsCmd Name) -> FreeVars methodNamesStmt (LastStmt cmd _) = methodNamesLCmd cmd methodNamesStmt (BodyStmt cmd _ _ _) = methodNamesLCmd cmd methodNamesStmt (BindStmt _ cmd _ _) = methodNamesLCmd cmd methodNamesStmt (RecStmt { recS_stmts = stmts }) = methodNamesStmts stmts `addOneFV` loopAName methodNamesStmt (LetStmt {}) = emptyFVs methodNamesStmt (ParStmt {}) = emptyFVs methodNamesStmt (TransStmt {}) = emptyFVs -- ParStmt and TransStmt can't occur in commands, but it's not convenient to error -- here so we just do what's convenient \end{code} %************************************************************************ %* * Arithmetic sequences %* * %************************************************************************ \begin{code} rnArithSeq :: ArithSeqInfo RdrName -> RnM (ArithSeqInfo Name, FreeVars) rnArithSeq (From expr) = do { (expr', fvExpr) <- rnLExpr expr ; return (From expr', fvExpr) } rnArithSeq (FromThen expr1 expr2) = do { (expr1', fvExpr1) <- rnLExpr expr1 ; (expr2', fvExpr2) <- rnLExpr expr2 ; return (FromThen expr1' expr2', fvExpr1 `plusFV` fvExpr2) } rnArithSeq (FromTo expr1 expr2) = do { (expr1', fvExpr1) <- rnLExpr expr1 ; (expr2', fvExpr2) <- rnLExpr expr2 ; return (FromTo expr1' expr2', fvExpr1 `plusFV` fvExpr2) } rnArithSeq (FromThenTo expr1 expr2 expr3) = do { (expr1', fvExpr1) <- rnLExpr expr1 ; (expr2', fvExpr2) <- rnLExpr expr2 ; (expr3', fvExpr3) <- rnLExpr expr3 ; return (FromThenTo expr1' expr2' expr3', plusFVs [fvExpr1, fvExpr2, fvExpr3]) } \end{code} %************************************************************************ %* * \subsubsection{@Stmt@s: in @do@ expressions} %* * %************************************************************************ \begin{code} rnStmts :: Outputable (body RdrName) => HsStmtContext Name -> (Located (body RdrName) -> RnM (Located (body Name), FreeVars)) -> [LStmt RdrName (Located (body RdrName))] -> ([Name] -> RnM (thing, FreeVars)) -> RnM (([LStmt Name (Located (body Name))], thing), FreeVars) -- Variables bound by the Stmts, and mentioned in thing_inside, -- do not appear in the result FreeVars rnStmts ctxt _ [] thing_inside = do { checkEmptyStmts ctxt ; (thing, fvs) <- thing_inside [] ; return (([], thing), fvs) } rnStmts MDoExpr rnBody stmts thing_inside -- Deal with mdo = -- Behave like do { rec { ...all but last... }; last } do { ((stmts1, (stmts2, thing)), fvs) <- rnStmt MDoExpr rnBody (noLoc $ mkRecStmt all_but_last) $ \ _ -> do { last_stmt' <- checkLastStmt MDoExpr last_stmt ; rnStmt MDoExpr rnBody last_stmt' thing_inside } ; return (((stmts1 ++ stmts2), thing), fvs) } where Just (all_but_last, last_stmt) = snocView stmts rnStmts ctxt rnBody (lstmt@(L loc _) : lstmts) thing_inside | null lstmts = setSrcSpan loc $ do { lstmt' <- checkLastStmt ctxt lstmt ; rnStmt ctxt rnBody lstmt' thing_inside } | otherwise = do { ((stmts1, (stmts2, thing)), fvs) <- setSrcSpan loc $ do { checkStmt ctxt lstmt ; rnStmt ctxt rnBody lstmt $ \ bndrs1 -> rnStmts ctxt rnBody lstmts $ \ bndrs2 -> thing_inside (bndrs1 ++ bndrs2) } ; return (((stmts1 ++ stmts2), thing), fvs) } ---------------------- rnStmt :: Outputable (body RdrName) => HsStmtContext Name -> (Located (body RdrName) -> RnM (Located (body Name), FreeVars)) -> LStmt RdrName (Located (body RdrName)) -> ([Name] -> RnM (thing, FreeVars)) -> RnM (([LStmt Name (Located (body Name))], thing), FreeVars) -- Variables bound by the Stmt, and mentioned in thing_inside, -- do not appear in the result FreeVars rnStmt ctxt rnBody (L loc (LastStmt body _)) thing_inside = do { (body', fv_expr) <- rnBody body ; (ret_op, fvs1) <- lookupStmtName ctxt returnMName ; (thing, fvs3) <- thing_inside [] ; return (([L loc (LastStmt body' ret_op)], thing), fv_expr `plusFV` fvs1 `plusFV` fvs3) } rnStmt ctxt rnBody (L loc (BodyStmt body _ _ _)) thing_inside = do { (body', fv_expr) <- rnBody body ; (then_op, fvs1) <- lookupStmtName ctxt thenMName ; (guard_op, fvs2) <- if isListCompExpr ctxt then lookupStmtName ctxt guardMName else return (noSyntaxExpr, emptyFVs) -- Only list/parr/monad comprehensions use 'guard' -- Also for sub-stmts of same eg [ e | x<-xs, gd | blah ] -- Here "gd" is a guard ; (thing, fvs3) <- thing_inside [] ; return (([L loc (BodyStmt body' then_op guard_op placeHolderType)], thing), fv_expr `plusFV` fvs1 `plusFV` fvs2 `plusFV` fvs3) } rnStmt ctxt rnBody (L loc (BindStmt pat body _ _)) thing_inside = do { (body', fv_expr) <- rnBody body -- The binders do not scope over the expression ; (bind_op, fvs1) <- lookupStmtName ctxt bindMName ; (fail_op, fvs2) <- lookupStmtName ctxt failMName ; rnPat (StmtCtxt ctxt) pat $ \ pat' -> do { (thing, fvs3) <- thing_inside (collectPatBinders pat') ; return (([L loc (BindStmt pat' body' bind_op fail_op)], thing), fv_expr `plusFV` fvs1 `plusFV` fvs2 `plusFV` fvs3) }} -- fv_expr shouldn't really be filtered by the rnPatsAndThen -- but it does not matter because the names are unique rnStmt _ _ (L loc (LetStmt binds)) thing_inside = do { rnLocalBindsAndThen binds $ \binds' -> do { (thing, fvs) <- thing_inside (collectLocalBinders binds') ; return (([L loc (LetStmt binds')], thing), fvs) } } rnStmt ctxt rnBody (L _ (RecStmt { recS_stmts = rec_stmts })) thing_inside = do { (return_op, fvs1) <- lookupStmtName ctxt returnMName ; (mfix_op, fvs2) <- lookupStmtName ctxt mfixName ; (bind_op, fvs3) <- lookupStmtName ctxt bindMName ; let empty_rec_stmt = emptyRecStmtName { recS_ret_fn = return_op , recS_mfix_fn = mfix_op , recS_bind_fn = bind_op } -- Step1: Bring all the binders of the mdo into scope -- (Remember that this also removes the binders from the -- finally-returned free-vars.) -- And rename each individual stmt, making a -- singleton segment. At this stage the FwdRefs field -- isn't finished: it's empty for all except a BindStmt -- for which it's the fwd refs within the bind itself -- (This set may not be empty, because we're in a recursive -- context.) ; rnRecStmtsAndThen rnBody rec_stmts $ \ segs -> do { let bndrs = nameSetToList $ foldr (unionNameSets . (\(ds,_,_,_) -> ds)) emptyNameSet segs ; (thing, fvs_later) <- thing_inside bndrs ; let (rec_stmts', fvs) = segmentRecStmts ctxt empty_rec_stmt segs fvs_later ; return ((rec_stmts', thing), fvs `plusFV` fvs1 `plusFV` fvs2 `plusFV` fvs3) } } rnStmt ctxt _ (L loc (ParStmt segs _ _)) thing_inside = do { (mzip_op, fvs1) <- lookupStmtName ctxt mzipName ; (bind_op, fvs2) <- lookupStmtName ctxt bindMName ; (return_op, fvs3) <- lookupStmtName ctxt returnMName ; ((segs', thing), fvs4) <- rnParallelStmts (ParStmtCtxt ctxt) return_op segs thing_inside ; return ( ([L loc (ParStmt segs' mzip_op bind_op)], thing) , fvs1 `plusFV` fvs2 `plusFV` fvs3 `plusFV` fvs4) } rnStmt ctxt _ (L loc (TransStmt { trS_stmts = stmts, trS_by = by, trS_form = form , trS_using = using })) thing_inside = do { -- Rename the 'using' expression in the context before the transform is begun (using', fvs1) <- rnLExpr using -- Rename the stmts and the 'by' expression -- Keep track of the variables mentioned in the 'by' expression ; ((stmts', (by', used_bndrs, thing)), fvs2) <- rnStmts (TransStmtCtxt ctxt) rnLExpr 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 -- The paper (Fig 5) has a bug here; we must treat any free varaible -- of the "thing inside", **or of the by-expression**, as used ; return ((by', used_bndrs, thing), fvs) } -- Lookup `return`, `(>>=)` and `liftM` for monad comprehensions ; (return_op, fvs3) <- lookupStmtName ctxt returnMName ; (bind_op, fvs4) <- lookupStmtName ctxt bindMName ; (fmap_op, fvs5) <- case form of ThenForm -> return (noSyntaxExpr, emptyFVs) _ -> lookupStmtName ctxt fmapName ; let all_fvs = fvs1 `plusFV` fvs2 `plusFV` fvs3 `plusFV` fvs4 `plusFV` fvs5 bndr_map = used_bndrs `zip` used_bndrs -- See Note [TransStmt binder map] in HsExpr ; traceRn (text "rnStmt: implicitly rebound these used binders:" <+> ppr bndr_map) ; return (([L loc (TransStmt { trS_stmts = stmts', trS_bndrs = bndr_map , trS_by = by', trS_using = using', trS_form = form , trS_ret = return_op, trS_bind = bind_op , trS_fmap = fmap_op })], thing), all_fvs) } rnParallelStmts :: forall thing. HsStmtContext Name -> SyntaxExpr Name -> [ParStmtBlock RdrName RdrName] -> ([Name] -> RnM (thing, FreeVars)) -> RnM (([ParStmtBlock Name Name], thing), FreeVars) -- Note [Renaming parallel Stmts] rnParallelStmts ctxt return_op segs thing_inside = do { orig_lcl_env <- getLocalRdrEnv ; rn_segs orig_lcl_env [] segs } where rn_segs :: LocalRdrEnv -> [Name] -> [ParStmtBlock RdrName RdrName] -> RnM (([ParStmtBlock Name 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 (ParStmtBlock stmts _ _ : segs) = do { ((stmts', (used_bndrs, segs', thing)), fvs) <- rnStmts ctxt rnLExpr 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' = ParStmtBlock stmts' used_bndrs return_op ; 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))) lookupStmtName :: HsStmtContext Name -> Name -> RnM (HsExpr Name, FreeVars) -- Like lookupSyntaxName, but ListComp/PArrComp are never rebindable -- Neither is ArrowExpr, which has its own desugarer in DsArrows lookupStmtName ctxt n = case ctxt of ListComp -> not_rebindable PArrComp -> not_rebindable ArrowExpr -> not_rebindable PatGuard {} -> not_rebindable DoExpr -> rebindable MDoExpr -> rebindable MonadComp -> rebindable GhciStmtCtxt -> rebindable -- I suppose? ParStmtCtxt c -> lookupStmtName c n -- Look inside to TransStmtCtxt c -> lookupStmtName c n -- the parent context where rebindable = lookupSyntaxName n not_rebindable = return (HsVar n, emptyFVs) \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. %************************************************************************ %* * \subsubsection{mdo expressions} %* * %************************************************************************ \begin{code} type FwdRefs = NameSet type Segment stmts = (Defs, Uses, -- May include defs FwdRefs, -- A subset of uses that are -- (a) used before they are bound in this segment, or -- (b) used here, and bound in subsequent segments stmts) -- Either Stmt or [Stmt] -- wrapper that does both the left- and right-hand sides rnRecStmtsAndThen :: Outputable (body RdrName) => (Located (body RdrName) -> RnM (Located (body Name), FreeVars)) -> [LStmt RdrName (Located (body RdrName))] -- assumes that the FreeVars returned includes -- the FreeVars of the Segments -> ([Segment (LStmt Name (Located (body Name)))] -> RnM (a, FreeVars)) -> RnM (a, FreeVars) rnRecStmtsAndThen rnBody s cont = do { -- (A) Make the mini fixity env for all of the stmts fix_env <- makeMiniFixityEnv (collectRecStmtsFixities s) -- (B) Do the LHSes ; new_lhs_and_fv <- rn_rec_stmts_lhs fix_env s -- ...bring them and their fixities into scope ; let bound_names = collectLStmtsBinders (map fst new_lhs_and_fv) -- Fake uses of variables introduced implicitly (warning suppression, see #4404) implicit_uses = lStmtsImplicits (map fst new_lhs_and_fv) ; bindLocalNamesFV bound_names $ addLocalFixities fix_env bound_names $ do -- (C) do the right-hand-sides and thing-inside { segs <- rn_rec_stmts rnBody bound_names new_lhs_and_fv ; (res, fvs) <- cont segs ; warnUnusedLocalBinds bound_names (fvs `unionNameSets` implicit_uses) ; return (res, fvs) }} -- get all the fixity decls in any Let stmt collectRecStmtsFixities :: [LStmtLR RdrName RdrName body] -> [LFixitySig RdrName] collectRecStmtsFixities l = foldr (\ s -> \acc -> case s of (L _ (LetStmt (HsValBinds (ValBindsIn _ sigs)))) -> foldr (\ sig -> \ acc -> case sig of (L loc (FixSig s)) -> (L loc s) : acc _ -> acc) acc sigs _ -> acc) [] l -- left-hand sides rn_rec_stmt_lhs :: Outputable body => MiniFixityEnv -> LStmt RdrName body -- rename LHS, and return its FVs -- Warning: we will only need the FreeVars below in the case of a BindStmt, -- so we don't bother to compute it accurately in the other cases -> RnM [(LStmtLR Name RdrName body, FreeVars)] rn_rec_stmt_lhs _ (L loc (BodyStmt body a b c)) = return [(L loc (BodyStmt body a b c), emptyFVs)] rn_rec_stmt_lhs _ (L loc (LastStmt body a)) = return [(L loc (LastStmt body a), emptyFVs)] rn_rec_stmt_lhs fix_env (L loc (BindStmt pat body a b)) = do -- should the ctxt be MDo instead? (pat', fv_pat) <- rnBindPat (localRecNameMaker fix_env) pat return [(L loc (BindStmt pat' body a b), fv_pat)] rn_rec_stmt_lhs _ (L _ (LetStmt binds@(HsIPBinds _))) = failWith (badIpBinds (ptext (sLit "an mdo expression")) binds) rn_rec_stmt_lhs fix_env (L loc (LetStmt (HsValBinds binds))) = do (_bound_names, binds') <- rnLocalValBindsLHS fix_env binds return [(L loc (LetStmt (HsValBinds binds')), -- Warning: this is bogus; see function invariant emptyFVs )] -- XXX Do we need to do something with the return and mfix names? rn_rec_stmt_lhs fix_env (L _ (RecStmt { recS_stmts = stmts })) -- Flatten Rec inside Rec = rn_rec_stmts_lhs fix_env stmts rn_rec_stmt_lhs _ stmt@(L _ (ParStmt {})) -- Syntactically illegal in mdo = pprPanic "rn_rec_stmt" (ppr stmt) rn_rec_stmt_lhs _ stmt@(L _ (TransStmt {})) -- Syntactically illegal in mdo = pprPanic "rn_rec_stmt" (ppr stmt) rn_rec_stmt_lhs _ (L _ (LetStmt EmptyLocalBinds)) = panic "rn_rec_stmt LetStmt EmptyLocalBinds" rn_rec_stmts_lhs :: Outputable body => MiniFixityEnv -> [LStmt RdrName body] -> RnM [(LStmtLR Name RdrName body, FreeVars)] rn_rec_stmts_lhs fix_env 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. ; checkDupNames boundNames ; return ls } -- right-hand-sides rn_rec_stmt :: (Outputable (body RdrName)) => (Located (body RdrName) -> RnM (Located (body Name), FreeVars)) -> [Name] -> LStmtLR Name RdrName (Located (body RdrName)) -> FreeVars -> RnM [Segment (LStmt Name (Located (body Name)))] -- Rename a Stmt that is inside a RecStmt (or mdo) -- Assumes all binders are already in scope -- Turns each stmt into a singleton Stmt rn_rec_stmt rnBody _ (L loc (LastStmt body _)) _ = do { (body', fv_expr) <- rnBody body ; (ret_op, fvs1) <- lookupSyntaxName returnMName ; return [(emptyNameSet, fv_expr `plusFV` fvs1, emptyNameSet, L loc (LastStmt body' ret_op))] } rn_rec_stmt rnBody _ (L loc (BodyStmt body _ _ _)) _ = do { (body', fvs) <- rnBody body ; (then_op, fvs1) <- lookupSyntaxName thenMName ; return [(emptyNameSet, fvs `plusFV` fvs1, emptyNameSet, L loc (BodyStmt body' then_op noSyntaxExpr placeHolderType))] } rn_rec_stmt rnBody _ (L loc (BindStmt pat' body _ _)) fv_pat = do { (body', fv_expr) <- rnBody body ; (bind_op, fvs1) <- lookupSyntaxName bindMName ; (fail_op, fvs2) <- lookupSyntaxName failMName ; let bndrs = mkNameSet (collectPatBinders pat') fvs = fv_expr `plusFV` fv_pat `plusFV` fvs1 `plusFV` fvs2 ; return [(bndrs, fvs, bndrs `intersectNameSet` fvs, L loc (BindStmt pat' body' bind_op fail_op))] } rn_rec_stmt _ _ (L _ (LetStmt binds@(HsIPBinds _))) _ = failWith (badIpBinds (ptext (sLit "an mdo expression")) binds) rn_rec_stmt _ all_bndrs (L loc (LetStmt (HsValBinds binds'))) _ = do (binds', du_binds) <- -- fixities and unused are handled above in rnRecStmtsAndThen rnLocalValBindsRHS (mkNameSet all_bndrs) binds' return [(duDefs du_binds, allUses du_binds, emptyNameSet, L loc (LetStmt (HsValBinds binds')))] -- no RecStmt case because they get flattened above when doing the LHSes rn_rec_stmt _ _ stmt@(L _ (RecStmt {})) _ = pprPanic "rn_rec_stmt: RecStmt" (ppr stmt) rn_rec_stmt _ _ stmt@(L _ (ParStmt {})) _ -- Syntactically illegal in mdo = pprPanic "rn_rec_stmt: ParStmt" (ppr stmt) rn_rec_stmt _ _ stmt@(L _ (TransStmt {})) _ -- Syntactically illegal in mdo = pprPanic "rn_rec_stmt: TransStmt" (ppr stmt) rn_rec_stmt _ _ (L _ (LetStmt EmptyLocalBinds)) _ = panic "rn_rec_stmt: LetStmt EmptyLocalBinds" rn_rec_stmts :: Outputable (body RdrName) => (Located (body RdrName) -> RnM (Located (body Name), FreeVars)) -> [Name] -> [(LStmtLR Name RdrName (Located (body RdrName)), FreeVars)] -> RnM [Segment (LStmt Name (Located (body Name)))] rn_rec_stmts rnBody bndrs stmts = do { segs_s <- mapM (uncurry (rn_rec_stmt rnBody bndrs)) stmts ; return (concat segs_s) } --------------------------------------------- segmentRecStmts :: HsStmtContext Name -> Stmt Name body -> [Segment (LStmt Name body)] -> FreeVars -> ([LStmt Name body], FreeVars) segmentRecStmts ctxt empty_rec_stmt segs fvs_later | MDoExpr <- ctxt = segsToStmts empty_rec_stmt grouped_segs fvs_later -- Step 4: Turn the segments into Stmts -- Use RecStmt when and only when there are fwd refs -- Also gather up the uses from the end towards the -- start, so we can tell the RecStmt which things are -- used 'after' the RecStmt | otherwise = ([ L (getLoc (head ss)) $ empty_rec_stmt { recS_stmts = ss , recS_later_ids = nameSetToList (defs `intersectNameSet` fvs_later) , recS_rec_ids = nameSetToList (defs `intersectNameSet` uses) }] , uses `plusFV` fvs_later) where (defs_s, uses_s, _, ss) = unzip4 segs defs = plusFVs defs_s uses = plusFVs uses_s -- Step 2: Fill in the fwd refs. -- The segments are all singletons, but their fwd-ref -- field mentions all the things used by the segment -- that are bound after their use segs_w_fwd_refs = addFwdRefs segs -- Step 3: Group together the segments to make bigger segments -- Invariant: in the result, no segment uses a variable -- bound in a later segment grouped_segs = glomSegments ctxt segs_w_fwd_refs ---------------------------- addFwdRefs :: [Segment a] -> [Segment a] -- So far the segments only have forward refs *within* the Stmt -- (which happens for bind: x <- ...x...) -- This function adds the cross-seg fwd ref info addFwdRefs segs = fst (foldr mk_seg ([], emptyNameSet) segs) where mk_seg (defs, uses, fwds, stmts) (segs, later_defs) = (new_seg : segs, all_defs) where new_seg = (defs, uses, new_fwds, stmts) all_defs = later_defs `unionNameSets` defs new_fwds = fwds `unionNameSets` (uses `intersectNameSet` later_defs) -- Add the downstream fwd refs here \end{code} Note [Segmenting mdo] ~~~~~~~~~~~~~~~~~~~~~ NB. June 7 2012: We only glom segments that appear in an explicit mdo; and leave those found in "do rec"'s intact. See http://ghc.haskell.org/trac/ghc/ticket/4148 for the discussion leading to this design choice. Hence the test in segmentRecStmts. Note [Glomming segments] ~~~~~~~~~~~~~~~~~~~~~~~~ Glomming the singleton segments of an mdo into minimal recursive groups. At first I thought this was just strongly connected components, but there's an important constraint: the order of the stmts must not change. Consider mdo { x <- ...y... p <- z y <- ...x... q <- x z <- y r <- x } Here, the first stmt mention 'y', which is bound in the third. But that means that the innocent second stmt (p <- z) gets caught up in the recursion. And that in turn means that the binding for 'z' has to be included... and so on. Start at the tail { r <- x } Now add the next one { z <- y ; r <- x } Now add one more { q <- x ; z <- y ; r <- x } Now one more... but this time we have to group a bunch into rec { rec { y <- ...x... ; q <- x ; z <- y } ; r <- x } Now one more, which we can add on without a rec { p <- z ; rec { y <- ...x... ; q <- x ; z <- y } ; r <- x } Finally we add the last one; since it mentions y we have to glom it together with the first two groups { rec { x <- ...y...; p <- z ; y <- ...x... ; q <- x ; z <- y } ; r <- x } \begin{code} glomSegments :: HsStmtContext Name -> [Segment (LStmt Name body)] -> [Segment [LStmt Name body]] -- See Note [Glomming segments] glomSegments _ [] = [] glomSegments ctxt ((defs,uses,fwds,stmt) : segs) -- Actually stmts will always be a singleton = (seg_defs, seg_uses, seg_fwds, seg_stmts) : others where segs' = glomSegments ctxt segs (extras, others) = grab uses segs' (ds, us, fs, ss) = unzip4 extras seg_defs = plusFVs ds `plusFV` defs seg_uses = plusFVs us `plusFV` uses seg_fwds = plusFVs fs `plusFV` fwds seg_stmts = stmt : concat ss grab :: NameSet -- The client -> [Segment a] -> ([Segment a], -- Needed by the 'client' [Segment a]) -- Not needed by the client -- The result is simply a split of the input grab uses dus = (reverse yeses, reverse noes) where (noes, yeses) = span not_needed (reverse dus) not_needed (defs,_,_,_) = not (intersectsNameSet defs uses) ---------------------------------------------------- segsToStmts :: Stmt Name body -- A RecStmt with the SyntaxOps filled in -> [Segment [LStmt Name body]] -> FreeVars -- Free vars used 'later' -> ([LStmt Name body], FreeVars) segsToStmts _ [] fvs_later = ([], fvs_later) segsToStmts empty_rec_stmt ((defs, uses, fwds, ss) : segs) fvs_later = ASSERT( not (null ss) ) (new_stmt : later_stmts, later_uses `plusFV` uses) where (later_stmts, later_uses) = segsToStmts empty_rec_stmt segs fvs_later new_stmt | non_rec = head ss | otherwise = L (getLoc (head ss)) rec_stmt rec_stmt = empty_rec_stmt { recS_stmts = ss , recS_later_ids = nameSetToList used_later , recS_rec_ids = nameSetToList fwds } non_rec = isSingleton ss && isEmptyNameSet fwds used_later = defs `intersectNameSet` later_uses -- The ones needed after the RecStmt \end{code} %************************************************************************ %* * \subsubsection{Assertion utils} %* * %************************************************************************ \begin{code} srcSpanPrimLit :: DynFlags -> SrcSpan -> HsExpr Name srcSpanPrimLit dflags span = HsLit (HsStringPrim (unsafeMkByteString (showSDocOneLine dflags (ppr span)))) mkAssertErrorExpr :: RnM (HsExpr Name) -- Return an expression for (assertError "Foo.hs:27") mkAssertErrorExpr = do sloc <- getSrcSpanM dflags <- getDynFlags return (HsApp (L sloc (HsVar assertErrorName)) (L sloc (srcSpanPrimLit dflags sloc))) \end{code} Note [Adding the implicit parameter to 'assert'] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The renamer transforms (assert e1 e2) to (assert "Foo.hs:27" e1 e2). By doing this in the renamer we allow the typechecker to just see the expanded application and do the right thing. But it's not really the Right Thing because there's no way to "undo" if you want to see the original source code. We'll have fix this in due course, when we care more about being able to reconstruct the exact original program. %************************************************************************ %* * \subsubsection{Errors} %* * %************************************************************************ \begin{code} checkEmptyStmts :: HsStmtContext Name -> RnM () -- We've seen an empty sequence of Stmts... is that ok? checkEmptyStmts ctxt = unless (okEmpty ctxt) (addErr (emptyErr ctxt)) okEmpty :: HsStmtContext a -> Bool okEmpty (PatGuard {}) = True okEmpty _ = False emptyErr :: HsStmtContext Name -> SDoc emptyErr (ParStmtCtxt {}) = ptext (sLit "Empty statement group in parallel comprehension") emptyErr (TransStmtCtxt {}) = ptext (sLit "Empty statement group preceding 'group' or 'then'") emptyErr ctxt = ptext (sLit "Empty") <+> pprStmtContext ctxt ---------------------- checkLastStmt :: Outputable (body RdrName) => HsStmtContext Name -> LStmt RdrName (Located (body RdrName)) -> RnM (LStmt RdrName (Located (body RdrName))) checkLastStmt ctxt lstmt@(L loc stmt) = case ctxt of ListComp -> check_comp MonadComp -> check_comp PArrComp -> check_comp ArrowExpr -> check_do DoExpr -> check_do MDoExpr -> check_do _ -> check_other where check_do -- Expect BodyStmt, and change it to LastStmt = case stmt of BodyStmt e _ _ _ -> return (L loc (mkLastStmt e)) LastStmt {} -> return lstmt -- "Deriving" clauses may generate a -- LastStmt directly (unlike the parser) _ -> do { addErr (hang last_error 2 (ppr stmt)); return lstmt } last_error = (ptext (sLit "The last statement in") <+> pprAStmtContext ctxt <+> ptext (sLit "must be an expression")) check_comp -- Expect LastStmt; this should be enforced by the parser! = case stmt of LastStmt {} -> return lstmt _ -> pprPanic "checkLastStmt" (ppr lstmt) check_other -- Behave just as if this wasn't the last stmt = do { checkStmt ctxt lstmt; return lstmt } -- Checking when a particular Stmt is ok checkStmt :: HsStmtContext Name -> LStmt RdrName (Located (body RdrName)) -> RnM () checkStmt ctxt (L _ stmt) = do { dflags <- getDynFlags ; case okStmt dflags ctxt stmt of IsValid -> return () NotValid extra -> addErr (msg $$ extra) } where msg = sep [ ptext (sLit "Unexpected") <+> pprStmtCat stmt <+> ptext (sLit "statement") , ptext (sLit "in") <+> pprAStmtContext ctxt ] pprStmtCat :: Stmt a body -> SDoc pprStmtCat (TransStmt {}) = ptext (sLit "transform") pprStmtCat (LastStmt {}) = ptext (sLit "return expression") pprStmtCat (BodyStmt {}) = ptext (sLit "body") pprStmtCat (BindStmt {}) = ptext (sLit "binding") pprStmtCat (LetStmt {}) = ptext (sLit "let") pprStmtCat (RecStmt {}) = ptext (sLit "rec") pprStmtCat (ParStmt {}) = ptext (sLit "parallel") ------------ emptyInvalid :: Validity -- Payload is the empty document emptyInvalid = NotValid empty okStmt, okDoStmt, okCompStmt, okParStmt, okPArrStmt :: DynFlags -> HsStmtContext Name -> Stmt RdrName (Located (body RdrName)) -> Validity -- Return Nothing if OK, (Just extra) if not ok -- The "extra" is an SDoc that is appended to an generic error message okStmt dflags ctxt stmt = case ctxt of PatGuard {} -> okPatGuardStmt stmt ParStmtCtxt ctxt -> okParStmt dflags ctxt stmt DoExpr -> okDoStmt dflags ctxt stmt MDoExpr -> okDoStmt dflags ctxt stmt ArrowExpr -> okDoStmt dflags ctxt stmt GhciStmtCtxt -> okDoStmt dflags ctxt stmt ListComp -> okCompStmt dflags ctxt stmt MonadComp -> okCompStmt dflags ctxt stmt PArrComp -> okPArrStmt dflags ctxt stmt TransStmtCtxt ctxt -> okStmt dflags ctxt stmt ------------- okPatGuardStmt :: Stmt RdrName (Located (body RdrName)) -> Validity okPatGuardStmt stmt = case stmt of BodyStmt {} -> IsValid BindStmt {} -> IsValid LetStmt {} -> IsValid _ -> emptyInvalid ------------- okParStmt dflags ctxt stmt = case stmt of LetStmt (HsIPBinds {}) -> emptyInvalid _ -> okStmt dflags ctxt stmt ---------------- okDoStmt dflags ctxt stmt = case stmt of RecStmt {} | Opt_RecursiveDo `xopt` dflags -> IsValid | ArrowExpr <- ctxt -> IsValid -- Arrows allows 'rec' | otherwise -> NotValid (ptext (sLit "Use RecursiveDo")) BindStmt {} -> IsValid LetStmt {} -> IsValid BodyStmt {} -> IsValid _ -> emptyInvalid ---------------- okCompStmt dflags _ stmt = case stmt of BindStmt {} -> IsValid LetStmt {} -> IsValid BodyStmt {} -> IsValid ParStmt {} | Opt_ParallelListComp `xopt` dflags -> IsValid | otherwise -> NotValid (ptext (sLit "Use ParallelListComp")) TransStmt {} | Opt_TransformListComp `xopt` dflags -> IsValid | otherwise -> NotValid (ptext (sLit "Use TransformListComp")) RecStmt {} -> emptyInvalid LastStmt {} -> emptyInvalid -- Should not happen (dealt with by checkLastStmt) ---------------- okPArrStmt dflags _ stmt = case stmt of BindStmt {} -> IsValid LetStmt {} -> IsValid BodyStmt {} -> IsValid ParStmt {} | Opt_ParallelListComp `xopt` dflags -> IsValid | otherwise -> NotValid (ptext (sLit "Use ParallelListComp")) TransStmt {} -> emptyInvalid RecStmt {} -> emptyInvalid LastStmt {} -> emptyInvalid -- Should not happen (dealt with by checkLastStmt) --------- checkTupleSection :: [HsTupArg RdrName] -> RnM () checkTupleSection args = do { tuple_section <- xoptM Opt_TupleSections ; checkErr (all tupArgPresent args || tuple_section) msg } where msg = ptext (sLit "Illegal tuple section: use TupleSections") --------- sectionErr :: HsExpr RdrName -> SDoc sectionErr expr = hang (ptext (sLit "A section must be enclosed in parentheses")) 2 (ptext (sLit "thus:") <+> (parens (ppr expr))) patSynErr :: HsExpr RdrName -> RnM (HsExpr Name, FreeVars) patSynErr e = do { addErr (sep [ptext (sLit "Pattern syntax in expression context:"), nest 4 (ppr e)]) ; return (EWildPat, emptyFVs) } badIpBinds :: Outputable a => SDoc -> a -> SDoc badIpBinds what binds = hang (ptext (sLit "Implicit-parameter bindings illegal in") <+> what) 2 (ppr binds) \end{code}