X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;ds=sidebyside;f=ghc%2Fcompiler%2FhsSyn%2FHsTypes.lhs;h=c65929715ccbce2ace38111711486909fc47011e;hb=911a9fad0e04c6df6e895bab8e169a90766dc483;hp=884ee9f8bef644e0663343f8b4647760886eae95;hpb=a77abe6a30ea2763cfa1c0ca83cdce9b7200ced2;p=ghc-hetmet.git diff --git a/ghc/compiler/hsSyn/HsTypes.lhs b/ghc/compiler/hsSyn/HsTypes.lhs index 884ee9f..c659297 100644 --- a/ghc/compiler/hsSyn/HsTypes.lhs +++ b/ghc/compiler/hsSyn/HsTypes.lhs @@ -1,271 +1,356 @@ -% -% (c) The GRASP/AQUA Project, Glasgow University, 1992-1996 +]% +% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998 % \section[HsTypes]{Abstract syntax: user-defined types} -If compiled without \tr{#define COMPILING_GHC}, you get -(part of) a Haskell-abstract-syntax library. With it, -you get part of GHC. - \begin{code} -#include "HsVersions.h" - module HsTypes ( - PolyType(..), MonoType(..), - Context(..), ClassAssertion(..) - -#ifdef COMPILING_GHC - , pprParendPolyType - , pprParendMonoType, pprContext - , extractMonoTyNames, extractCtxtTyNames - , cmpPolyType, cmpMonoType, cmpContext -#endif + HsType(..), LHsType, + HsTyVarBndr(..), LHsTyVarBndr, + HsExplicitForAll(..), + HsContext, LHsContext, + HsPred(..), LHsPred, + + mkExplicitHsForAllTy, mkImplicitHsForAllTy, + hsTyVarName, hsTyVarNames, replaceTyVarName, + hsLTyVarName, hsLTyVarNames, hsLTyVarLocName, hsLTyVarLocNames, + splitHsInstDeclTy, + + -- Type place holder + PostTcType, placeHolderType, + + -- Name place holder + SyntaxName, placeHolderName, + + -- Printing + pprParendHsType, pprHsForAll, pprHsContext, ppr_hs_context, pprHsTyVarBndr ) where -#ifdef COMPILING_GHC -import Ubiq +#include "HsVersions.h" + +import {-# SOURCE #-} HsExpr ( HsSplice, pprSplice ) + +import TcType ( Type, Kind, liftedTypeKind, eqKind ) +import Type ( {- instance Outputable Kind -}, pprParendKind, pprKind ) +import Name ( Name, mkInternalName ) +import OccName ( mkVarOcc ) +import BasicTypes ( IPName, Boxity, tupleParens ) +import PrelNames ( unboundKey ) +import SrcLoc ( noSrcLoc, Located(..), unLoc, noSrcSpan ) +import CmdLineOpts ( opt_PprStyle_Debug ) +import Outputable +\end{code} + + +%************************************************************************ +%* * +\subsection{Annotating the syntax} +%* * +%************************************************************************ + +\begin{code} +type PostTcType = Type -- Used for slots in the abstract syntax + -- where we want to keep slot for a type + -- to be added by the type checker...but + -- before typechecking it's just bogus -import Outputable ( interppSP, ifnotPprForUser ) -import Pretty -import Type ( Kind ) -import Util ( thenCmp, cmpList, isIn, panic# ) +placeHolderType :: PostTcType -- Used before typechecking +placeHolderType = panic "Evaluated the place holder for a PostTcType" -#endif {- COMPILING_GHC -} + +type SyntaxName = Name -- These names are filled in by the renamer + -- Before then they are a placeHolderName (so that + -- we can still print the HsSyn) + -- They correspond to "rebindable syntax"; + -- See RnEnv.lookupSyntaxName + +placeHolderName :: SyntaxName +placeHolderName = mkInternalName unboundKey + (mkVarOcc FSLIT("syntaxPlaceHolder")) + noSrcLoc \end{code} + +%************************************************************************ +%* * +\subsection{Data types} +%* * +%************************************************************************ + This is the syntax for types as seen in type signatures. \begin{code} -data PolyType name - = HsPreForAllTy (Context name) - (MonoType name) +type LHsContext name = Located (HsContext name) + +type HsContext name = [LHsPred name] + +type LHsPred name = Located (HsPred name) + +data HsPred name = HsClassP name [LHsType name] + | HsIParam (IPName name) (LHsType name) + +type LHsType name = Located (HsType name) + +data HsType name + = HsForAllTy HsExplicitForAll -- Renamer leaves this flag unchanged, to record the way + -- the user wrote it originally, so that the printer can + -- print it as the user wrote it + [LHsTyVarBndr name] -- With ImplicitForAll, this is the empty list + -- until the renamer fills in the variables + (LHsContext name) + (LHsType name) + + | HsTyVar name -- Type variable or type constructor + + | HsAppTy (LHsType name) + (LHsType name) + + | HsFunTy (LHsType name) -- function type + (LHsType name) + + | HsListTy (LHsType name) -- Element type + + | HsPArrTy (LHsType name) -- Elem. type of parallel array: [:t:] + + | HsTupleTy Boxity + [LHsType name] -- Element types (length gives arity) + + | HsOpTy (LHsType name) (Located name) (LHsType name) - -- The renamer turns HsPreForAllTys into HsForAllTys when they - -- occur in signatures, to make the binding of variables - -- explicit. This distinction is made visible for - -- non-COMPILING_GHC code, because you probably want to do the - -- same thing. + | HsParTy (LHsType name) + -- Parenthesis preserved for the precedence re-arrangement in RnTypes + -- It's important that a * (b + c) doesn't get rearranged to (a*b) + c! + -- + -- However, NB that toHsType doesn't add HsParTys (in an effort to keep + -- interface files smaller), so when printing a HsType we may need to + -- add parens. - | HsForAllTy [name] - (Context name) - (MonoType name) + | HsNumTy Integer -- Generics only -type Context name = [ClassAssertion name] + | HsPredTy (LHsPred name) -- Only used in the type of an instance + -- declaration, eg. Eq [a] -> Eq a + -- ^^^^ + -- HsPredTy -type ClassAssertion name = (name, name) + | HsKindSig (LHsType name) -- (ty :: kind) + Kind -- A type with a kind signature -data MonoType name - = MonoTyVar name -- Type variable + | HsSpliceTy (HsSplice name) - | MonoTyApp name -- Type constructor or variable - [MonoType name] +data HsExplicitForAll = Explicit | Implicit - -- We *could* have a "MonoTyCon name" equiv to "MonoTyApp name []" - -- (for efficiency, what?) WDP 96/02/18 +----------------------- +-- Combine adjacent for-alls. +-- The following awkward situation can happen otherwise: +-- f :: forall a. ((Num a) => Int) +-- might generate HsForAll (Just [a]) [] (HsForAll Nothing [Num a] t) +-- Then a isn't discovered as ambiguous, and we abstract the AbsBinds wrt [] +-- but the export list abstracts f wrt [a]. Disaster. +-- +-- A valid type must have one for-all at the top of the type, or of the fn arg types - | MonoFunTy (MonoType name) -- function type - (MonoType name) +mkImplicitHsForAllTy ctxt ty = mkHsForAllTy Implicit [] ctxt ty +mkExplicitHsForAllTy tvs ctxt ty = mkHsForAllTy Explicit tvs ctxt ty - | MonoListTy (MonoType name) -- list type - | MonoTupleTy [MonoType name] -- tuple type (length gives arity) +mkHsForAllTy :: HsExplicitForAll -> [LHsTyVarBndr name] -> LHsContext name -> LHsType name -> HsType name +-- Smart constructor for HsForAllTy +mkHsForAllTy exp tvs (L _ []) ty = mk_forall_ty exp tvs ty +mkHsForAllTy exp tvs ctxt ty = HsForAllTy exp tvs ctxt ty -#ifdef COMPILING_GHC - -- these next two are only used in unfoldings in interfaces - | MonoDictTy name -- Class - (MonoType name) +-- mk_forall_ty makes a pure for-all type (no context) +mk_forall_ty Explicit [] ty = unLoc ty -- Explicit for-all with no tyvars +mk_forall_ty exp tvs (L _ (HsParTy ty)) = mk_forall_ty exp tvs ty +mk_forall_ty exp1 tvs1 (L _ (HsForAllTy exp2 tvs2 ctxt ty)) = mkHsForAllTy (exp1 `plus` exp2) (tvs1 ++ tvs2) ctxt ty +mk_forall_ty exp tvs ty = HsForAllTy exp tvs (L noSrcSpan []) ty - | MonoForAllTy [(name, Kind)] - (MonoType name) +Implicit `plus` Implicit = Implicit +exp1 `plus` exp2 = Explicit + +type LHsTyVarBndr name = Located (HsTyVarBndr name) + +data HsTyVarBndr name + = UserTyVar name + | KindedTyVar name Kind -- *** NOTA BENE *** A "monotype" in a pragma can have -- for-alls in it, (mostly to do with dictionaries). These -- must be explicitly Kinded. -#endif {- COMPILING_GHC -} +hsTyVarName :: HsTyVarBndr name -> name +hsTyVarName (UserTyVar n) = n +hsTyVarName (KindedTyVar n _) = n + +hsLTyVarName :: LHsTyVarBndr name -> name +hsLTyVarName = hsTyVarName . unLoc + +hsTyVarNames :: [HsTyVarBndr name] -> [name] +hsTyVarNames tvs = map hsTyVarName tvs + +hsLTyVarNames :: [LHsTyVarBndr name] -> [name] +hsLTyVarNames = map hsLTyVarName + +hsLTyVarLocName :: LHsTyVarBndr name -> Located name +hsLTyVarLocName = fmap hsTyVarName + +hsLTyVarLocNames :: [LHsTyVarBndr name] -> [Located name] +hsLTyVarLocNames = map hsLTyVarLocName + +replaceTyVarName :: HsTyVarBndr name1 -> name2 -> HsTyVarBndr name2 +replaceTyVarName (UserTyVar n) n' = UserTyVar n' +replaceTyVarName (KindedTyVar n k) n' = KindedTyVar n' k \end{code} -This is used in various places: + \begin{code} -#ifdef COMPILING_GHC -pprContext :: (Outputable name) => PprStyle -> (Context name) -> Pretty - -pprContext sty [] = ppNil -pprContext sty [(clas, ty)] = ppCat [ppr sty clas, ppr sty ty, ppStr "=>"] -pprContext sty context - = ppBesides [ppLparen, - ppInterleave ppComma (map pp_assert context), - ppRparen, ppStr " =>"] +splitHsInstDeclTy + :: OutputableBndr name + => HsType name + -> ([LHsTyVarBndr name], HsContext name, name, [LHsType name]) + -- Split up an instance decl type, returning the pieces + +-- In interface files, the instance declaration head is created +-- by HsTypes.toHsType, which does not guarantee to produce a +-- HsForAllTy. For example, if we had the weird decl +-- instance Foo T => Foo [T] +-- then we'd get the instance type +-- Foo T -> Foo [T] +-- So when colleting the instance context, to be on the safe side +-- we gather predicate arguments +-- +-- For source code, the parser ensures the type will have the right shape. +-- (e.g. see ParseUtil.checkInstType) + +splitHsInstDeclTy inst_ty + = case inst_ty of + HsForAllTy _ tvs cxt1 tau -- The type vars should have been + -- computed by now, even if they were implicit + -> (tvs, unLoc cxt1 ++ cxt2, cls, tys) + where + (cxt2, cls, tys) = split_tau (unLoc tau) + + other -> ([], cxt2, cls, tys) + where + (cxt2, cls, tys) = split_tau inst_ty + where - pp_assert (clas, ty) - = ppCat [ppr sty clas, ppr sty ty] + split_tau (HsFunTy (L _ (HsPredTy p)) ty) = (p:ps, cls, tys) + where + (ps, cls, tys) = split_tau (unLoc ty) + split_tau (HsPredTy (L _ (HsClassP cls tys))) = ([], cls, tys) + split_tau other = pprPanic "splitHsInstDeclTy" (ppr inst_ty) \end{code} -\begin{code} -instance (Outputable name) => Outputable (PolyType name) where - ppr sty (HsPreForAllTy ctxt ty) - = print_it sty ppNil ctxt ty - ppr sty (HsForAllTy [] ctxt ty) - = print_it sty ppNil ctxt ty - ppr sty (HsForAllTy tvs ctxt ty) - = print_it sty - (ppBesides [ppStr "_forall_ ", interppSP sty tvs, ppStr " => "]) - ctxt ty - -print_it sty pp_forall ctxt ty - = ppCat [ifnotPprForUser sty pp_forall, -- print foralls unless PprForUser - pprContext sty ctxt, ppr sty ty] - -pprParendPolyType :: Outputable name => PprStyle -> PolyType name -> Pretty -pprParendPolyType sty ty = ppr sty ty -- ToDo: more later - -instance (Outputable name) => Outputable (MonoType name) where - ppr = pprMonoType - -pREC_TOP = (0 :: Int) -pREC_FUN = (1 :: Int) -pREC_CON = (2 :: Int) - --- printing works more-or-less as for Types -pprMonoType, pprParendMonoType :: (Outputable name) => PprStyle -> MonoType name -> Pretty +%************************************************************************ +%* * +\subsection{Pretty printing} +%* * +%************************************************************************ -pprMonoType sty ty = ppr_mono_ty sty pREC_TOP ty -pprParendMonoType sty ty = ppr_mono_ty sty pREC_CON ty +NB: these types get printed into interface files, so + don't change the printing format lightly -ppr_mono_ty sty ctxt_prec (MonoTyVar name) = ppr sty name +\begin{code} +instance (OutputableBndr name) => Outputable (HsType name) where + ppr ty = pprHsType ty -ppr_mono_ty sty ctxt_prec (MonoFunTy ty1 ty2) - = let p1 = ppr_mono_ty sty pREC_FUN ty1 - p2 = ppr_mono_ty sty pREC_TOP ty2 - in - if ctxt_prec < pREC_FUN then -- no parens needed - ppSep [p1, ppBeside (ppStr "-> ") p2] - else - ppSep [ppBeside ppLparen p1, ppBesides [ppStr "-> ", p2, ppRparen]] - -ppr_mono_ty sty ctxt_prec (MonoTupleTy tys) - = ppBesides [ppLparen, ppInterleave ppComma (map (ppr sty) tys), ppRparen] - -ppr_mono_ty sty ctxt_prec (MonoListTy ty) - = ppBesides [ppLbrack, ppr_mono_ty sty pREC_TOP ty, ppRbrack] - -ppr_mono_ty sty ctxt_prec (MonoTyApp tycon tys) - = let pp_tycon = ppr sty tycon in - if null tys then - pp_tycon - else if ctxt_prec < pREC_CON then -- no parens needed - ppCat [pp_tycon, ppInterleave ppNil (map (ppr_mono_ty sty pREC_CON) tys)] - else - ppBesides [ ppLparen, pp_tycon, ppSP, - ppInterleave ppNil (map (ppr_mono_ty sty pREC_CON) tys), ppRparen ] - --- unfoldings only -ppr_mono_ty sty ctxt_prec (MonoDictTy clas ty) - = ppBesides [ppStr "{{", ppr sty clas, ppSP, ppr_mono_ty sty ctxt_prec ty, ppStr "}}"] - -#endif {- COMPILING_GHC -} -\end{code} +instance (Outputable name) => Outputable (HsTyVarBndr name) where + ppr (UserTyVar name) = ppr name + ppr (KindedTyVar name kind) = pprHsTyVarBndr name kind -\begin{code} -#ifdef COMPILING_GHC +instance OutputableBndr name => Outputable (HsPred name) where + ppr (HsClassP clas tys) = ppr clas <+> hsep (map (pprParendHsType.unLoc) tys) + ppr (HsIParam n ty) = hsep [ppr n, dcolon, ppr ty] -extractCtxtTyNames :: Eq name => Context name -> [name] -extractMonoTyNames :: Eq name => (name -> Bool) -> MonoType name -> [name] +pprHsTyVarBndr :: Outputable name => name -> Kind -> SDoc +pprHsTyVarBndr name kind | kind `eqKind` liftedTypeKind = ppr name + | otherwise = hsep [ppr name, dcolon, pprParendKind kind] -extractCtxtTyNames ctxt - = foldr get [] ctxt +pprHsForAll exp tvs cxt + | show_forall = forall_part <+> pprHsContext (unLoc cxt) + | otherwise = pprHsContext (unLoc cxt) where - get (clas, tv) acc - | tv `is_elem` acc = acc - | otherwise = tv : acc + show_forall = opt_PprStyle_Debug + || (not (null tvs) && is_explicit) + is_explicit = case exp of {Explicit -> True; Implicit -> False} + forall_part = ptext SLIT("forall") <+> interppSP tvs <> dot - is_elem = isIn "extractCtxtTyNames" +pprHsContext :: (OutputableBndr name) => HsContext name -> SDoc +pprHsContext [] = empty +pprHsContext cxt = ppr_hs_context cxt <+> ptext SLIT("=>") -extractMonoTyNames is_tyvar_name ty - = get ty [] - where - get (MonoTyApp con tys) acc = let - rest = foldr get acc tys - in - if is_tyvar_name con && not (con `is_elem` rest) - then con : rest - else rest - get (MonoListTy ty) acc = get ty acc - get (MonoFunTy ty1 ty2) acc = get ty1 (get ty2 acc) - get (MonoDictTy _ ty) acc = get ty acc - get (MonoTupleTy tys) acc = foldr get acc tys - get (MonoTyVar tv) acc - | tv `is_elem` acc = acc - | otherwise = tv : acc - - is_elem = isIn "extractMonoTyNames" - -#endif {- COMPILING_GHC -} +ppr_hs_context [] = empty +ppr_hs_context cxt = parens (interpp'SP cxt) \end{code} -We do define a specialised equality for these \tr{*Type} types; used -in checking interfaces. Most any other use is likely to be {\em -wrong}, so be careful! \begin{code} -#ifdef COMPILING_GHC - -cmpPolyType :: (a -> a -> TAG_) -> PolyType a -> PolyType a -> TAG_ -cmpMonoType :: (a -> a -> TAG_) -> MonoType a -> MonoType a -> TAG_ -cmpContext :: (a -> a -> TAG_) -> Context a -> Context a -> TAG_ - --- We assume that HsPreForAllTys have been smashed by now. -# ifdef DEBUG -cmpPolyType _ (HsPreForAllTy _ _) _ = panic# "cmpPolyType:HsPreForAllTy:1st arg" -cmpPolyType _ _ (HsPreForAllTy _ _) = panic# "cmpPolyType:HsPreForAllTy:2nd arg" -# endif +pREC_TOP = (0 :: Int) -- type in ParseIface.y +pREC_FUN = (1 :: Int) -- btype in ParseIface.y + -- Used for LH arg of (->) +pREC_OP = (2 :: Int) -- Used for arg of any infix operator + -- (we don't keep their fixities around) +pREC_CON = (3 :: Int) -- Used for arg of type applicn: + -- always parenthesise unless atomic + +maybeParen :: Int -- Precedence of context + -> Int -- Precedence of top-level operator + -> SDoc -> SDoc -- Wrap in parens if (ctxt >= op) +maybeParen ctxt_prec op_prec p | ctxt_prec >= op_prec = parens p + | otherwise = p + +-- printing works more-or-less as for Types -cmpPolyType cmp (HsForAllTy tvs1 c1 t1) (HsForAllTy tvs2 c2 t2) - = thenCmp (cmp_tvs tvs1 tvs2) - (thenCmp (cmpContext cmp c1 c2) (cmpMonoType cmp t1 t2)) - where - cmp_tvs [] [] = EQ_ - cmp_tvs [] _ = LT_ - cmp_tvs _ [] = GT_ - cmp_tvs (a:as) (b:bs) - = thenCmp (cmp a b) (cmp_tvs as bs) - cmp_tvs _ _ = panic# "cmp_tvs" - ------------ -cmpMonoType cmp (MonoTyVar n1) (MonoTyVar n2) - = cmp n1 n2 - -cmpMonoType cmp (MonoTupleTy tys1) (MonoTupleTy tys2) - = cmpList (cmpMonoType cmp) tys1 tys2 -cmpMonoType cmp (MonoListTy ty1) (MonoListTy ty2) - = cmpMonoType cmp ty1 ty2 - -cmpMonoType cmp (MonoTyApp tc1 tys1) (MonoTyApp tc2 tys2) - = thenCmp (cmp tc1 tc2) (cmpList (cmpMonoType cmp) tys1 tys2) - -cmpMonoType cmp (MonoFunTy a1 b1) (MonoFunTy a2 b2) - = thenCmp (cmpMonoType cmp a1 a2) (cmpMonoType cmp b1 b2) - -cmpMonoType cmp (MonoDictTy c1 ty1) (MonoDictTy c2 ty2) - = thenCmp (cmp c1 c2) (cmpMonoType cmp ty1 ty2) - -cmpMonoType cmp ty1 ty2 -- tags must be different - = let tag1 = tag ty1 - tag2 = tag ty2 +pprHsType, pprParendHsType :: (OutputableBndr name) => HsType name -> SDoc + +pprHsType ty = getPprStyle $ \sty -> ppr_mono_ty pREC_TOP (prepare sty ty) +pprParendHsType ty = ppr_mono_ty pREC_CON ty + +-- Before printing a type +-- (a) Remove outermost HsParTy parens +-- (b) Drop top-level for-all type variables in user style +-- since they are implicit in Haskell +prepare sty (HsParTy ty) = prepare sty (unLoc ty) +prepare sty ty = ty + +ppr_mono_lty ctxt_prec ty = ppr_mono_ty ctxt_prec (unLoc ty) + +ppr_mono_ty ctxt_prec (HsForAllTy exp tvs ctxt ty) + = maybeParen ctxt_prec pREC_FUN $ + sep [pprHsForAll exp tvs ctxt, ppr_mono_lty pREC_TOP ty] + +ppr_mono_ty ctxt_prec (HsTyVar name) = ppr name +ppr_mono_ty ctxt_prec (HsFunTy ty1 ty2) = ppr_fun_ty ctxt_prec ty1 ty2 +ppr_mono_ty ctxt_prec (HsTupleTy con tys) = tupleParens con (interpp'SP tys) +ppr_mono_ty ctxt_prec (HsKindSig ty kind) = parens (ppr_mono_lty pREC_TOP ty <+> dcolon <+> pprKind kind) +ppr_mono_ty ctxt_prec (HsListTy ty) = brackets (ppr_mono_lty pREC_TOP ty) +ppr_mono_ty ctxt_prec (HsPArrTy ty) = pabrackets (ppr_mono_lty pREC_TOP ty) +ppr_mono_ty ctxt_prec (HsPredTy pred) = braces (ppr pred) +ppr_mono_ty ctxt_prec (HsNumTy n) = integer n -- generics only +ppr_mono_ty ctxt_prec (HsSpliceTy s) = pprSplice s + +ppr_mono_ty ctxt_prec (HsAppTy fun_ty arg_ty) + = maybeParen ctxt_prec pREC_CON $ + hsep [ppr_mono_lty pREC_FUN fun_ty, ppr_mono_lty pREC_CON arg_ty] + +ppr_mono_ty ctxt_prec (HsOpTy ty1 op ty2) + = maybeParen ctxt_prec pREC_OP $ + ppr_mono_lty pREC_OP ty1 <+> ppr op <+> ppr_mono_lty pREC_OP ty2 + +ppr_mono_ty ctxt_prec (HsParTy ty) + = parens (ppr_mono_lty pREC_TOP ty) + -- Put the parens in where the user did + -- But we still use the precedence stuff to add parens because + -- toHsType doesn't put in any HsParTys, so we may still need them + +-------------------------- +ppr_fun_ty ctxt_prec ty1 ty2 + = let p1 = ppr_mono_lty pREC_FUN ty1 + p2 = ppr_mono_lty pREC_TOP ty2 in - if tag1 _LT_ tag2 then LT_ else GT_ - where - tag (MonoTyVar n1) = (ILIT(1) :: FAST_INT) - tag (MonoTupleTy tys1) = ILIT(2) - tag (MonoListTy ty1) = ILIT(3) - tag (MonoTyApp tc1 tys1) = ILIT(4) - tag (MonoFunTy a1 b1) = ILIT(5) - tag (MonoDictTy c1 ty1) = ILIT(7) - -------------------- -cmpContext cmp a b - = cmpList cmp_ctxt a b - where - cmp_ctxt (c1, tv1) (c2, tv2) - = thenCmp (cmp c1 c2) (cmp tv1 tv2) + maybeParen ctxt_prec pREC_FUN $ + sep [p1, ptext SLIT("->") <+> p2] -#endif {- COMPILING_GHC -} +-------------------------- +pabrackets p = ptext SLIT("[:") <> p <> ptext SLIT(":]") \end{code} + +