ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maeder

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maeder{- HetCATS/HasCASL/TypeDecl.hs

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maeder $Id$

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maeder Authors: Christian Maeder

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maeder Year: 2003

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maeder

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maeder analyse type decls

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maeder-}

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maeder

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maedermodule HasCASL.TypeDecl where

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maederimport HasCASL.As

bcd232120234d3cbbfd730b64a5a165f5c16e2a9Christian Maederimport HasCASL.AsUtils

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maederimport Common.AS_Annotation(item)

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maederimport HasCASL.ClassAna

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maederimport HasCASL.ClassDecl

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maederimport qualified Common.Lib.Map as Map

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maederimport Common.Id

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maederimport HasCASL.Le

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maederimport Data.Maybe

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maederimport Common.Lib.State

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maeder

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maederimport Common.Lib.Parsec

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maederimport Common.Lib.Parsec.Error

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maeder

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maederimport Common.Result

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maederimport Common.PrettyPrint

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maederimport HasCASL.TypeAna

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maederimport HasCASL.DataAna

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maederimport HasCASL.Reader

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maederimport HasCASL.Unify

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maeder

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maeder-- ---------------------------------------------------------------------------

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maeder-- analyse types as state

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maeder-- ---------------------------------------------------------------------------

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maeder

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian MaederfromReadR :: a -> ReadR (ClassMap, TypeMap) a -> State Env a

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian MaederfromReadR a r = toState a ( \ e -> (classMap e, typeMap e)) r

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian MaederanaTypeS :: (Kind, Type) -> State Env (Kind, Type)

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian MaederanaTypeS kt = fromReadR kt $ anaType kt

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder-- check with merge

bcd232120234d3cbbfd730b64a5a165f5c16e2a9Christian MaedercompatibleTypeDefn :: TypeDefn -> TypeDefn -> Id -> [Diagnosis]

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian MaedercompatibleTypeDefn d1 d2 i =

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maeder if case (d1, d2) of

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder (TypeVarDefn, TypeVarDefn) -> True

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maeder (TypeVarDefn, _) -> False

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder (_, TypeVarDefn) -> False

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maeder _ -> True

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maeder then [] else [mkDiag Error "incompatible redeclaration of type" i]

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maeder-- ---------------------------------------------------------------------------

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maeder-- storing type ids with their kind and definition

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maeder-- ---------------------------------------------------------------------------

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maeder-- | store a complete type map

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian MaederputTypeMap :: TypeMap -> State Env ()

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian MaederputTypeMap tk = do { e <- get; put e { typeMap = tk } }

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maeder

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder-- | store type id and check the kind

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian MaederaddTypeId :: TypeDefn -> Instance -> Kind -> Id -> State Env ()

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maeder-- type args not yet considered for kind construction

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian MaederaddTypeId defn _ kind i@(Id ts _ _) =

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maeder do nk <- toState kind classMap $ expandKind kind

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maeder let n = length $ filter isPlace ts

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maeder if n <= kindArity TopLevel nk then

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maeder addTypeKind defn i kind

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maeder else addDiag $ mkDiag Error "wrong arity of" i

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maeder

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maeder-- | store prefix type ids both with and without following places

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian MaederaddTypeKind :: TypeDefn -> Id -> Kind -> State Env ()

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian MaederaddTypeKind d i k =

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maeder if isPrefix i then do addSingleTypeKind d i k

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maeder addSingleTypeKind d (stripFinalPlaces i) k

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maeder else addSingleTypeKind d i k

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maeder-- | store type as is

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian MaederaddSingleTypeKind :: TypeDefn -> Id -> Kind -> State Env ()

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian MaederaddSingleTypeKind d i k =

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maeder do tk <- gets typeMap

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maeder case Map.lookup i tk of

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maeder Nothing -> putTypeMap $ Map.insert i

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maeder (TypeInfo k [] [] d) tk

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder Just (TypeInfo ok ks sups defn) ->

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maeder -- check with merge

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maeder do checkKindsS i k ok

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maeder if any (==k) (ok:ks)

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder then addDiag $ mkDiag Warning

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder "redeclared type" i

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder else putTypeMap $ Map.insert i

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder (TypeInfo ok

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder (k:ks) sups defn) tk

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder-- | add a supertype to a given type id

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian MaederaddSuperType :: Type -> Id -> State Env ()

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian MaederaddSuperType t i =

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder do tk <- gets typeMap

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maeder case Map.lookup i tk of

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder Nothing -> return () -- previous error

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder Just (TypeInfo ok ks sups defn) ->

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder putTypeMap $ Map.insert i

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder (TypeInfo ok ks (t:sups) defn)

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder tk

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder-- ---------------------------------------------------------------------------

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder-- analyse type items

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder-- ---------------------------------------------------------------------------

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian MaederanaTypeItem :: GenKind -> Instance -> TypeItem -> State Env ()

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian MaederanaTypeItem _ inst (TypeDecl pats kind _) =

9eaf4ea0944f7c5a1773c5f3c066f0117ece22dbChristian Maeder do anaKindS kind

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder let Result ds (Just is) = convertTypePatterns pats

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder appendDiags ds

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maeder mapM_ (addTypeId NoTypeDefn inst kind) is

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian MaederanaTypeItem _ inst (SubtypeDecl pats t _) =

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder do anaTypeS (star, t)

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maeder let Result ds (Just is) = convertTypePatterns pats

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder appendDiags ds

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder mapM_ (addTypeId NoTypeDefn inst star) is

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder mapM_ (addSuperType t) is

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian MaederanaTypeItem _ inst (IsoDecl pats _) =

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder do let Result ds (Just is) = convertTypePatterns pats

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder appendDiags ds

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder mapM_ (addTypeId NoTypeDefn inst star) is

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder mapM_ ( \ i -> mapM_ (addSuperType (TypeName i star 0)) is) is

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian MaederanaTypeItem _ inst (SubtypeDefn pat v t f ps) =

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder do (k, newT) <- anaTypeS (star, t)

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder checkKindsS t star k

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder addDiag $ Diag Warning ("unchecked formula '" ++ showPretty f "'")

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder $ firstPos [v] ps

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder let Result ds m = convertTypePattern pat

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder appendDiags ds

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maeder case m of

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder Nothing -> return ()

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder Just i -> do addTypeId (Supertype v newT $ item f)

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder inst k i

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder addSuperType newT i

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian MaederanaTypeItem _ inst (AliasType pat mk sc _) =

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder do (ik, newPty) <- anaPseudoType mk sc

9eaf4ea0944f7c5a1773c5f3c066f0117ece22dbChristian Maeder let Result ds m = convertTypePattern pat

9eaf4ea0944f7c5a1773c5f3c066f0117ece22dbChristian Maeder appendDiags ds

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder case m of

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder Just i -> addTypeId (AliasTypeDefn newPty) inst ik i

ea03c5d09694b4a966fbd19d46cfa5772648d95fChristian Maeder _ -> return ()

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian MaederanaTypeItem gk inst (Datatype d) = anaDatatype gk inst d

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian Maeder

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian MaederanaDatatype :: GenKind -> Instance -> DatatypeDecl -> State Env ()

502ed7ed7fecd10b6d0c83cdd48a244ec45e840aChristian MaederanaDatatype genKind inst (DatatypeDecl pat kind alts derivs _) =

9eaf4ea0944f7c5a1773c5f3c066f0117ece22dbChristian Maeder do k <- anaKindS kind

9eaf4ea0944f7c5a1773c5f3c066f0117ece22dbChristian Maeder checkKindsS pat star k

9eaf4ea0944f7c5a1773c5f3c066f0117ece22dbChristian Maeder case derivs of

Just c -> do (dk, _) <- anaClassS (star, c)

checkKindsS c star dk

Nothing -> return ()

let Result ds m = convertTypePattern pat

appendDiags ds

case m of

Nothing -> return ()

Just i ->

do let dt = TypeName i k 0

newAlts <- fromReadR [] $ anaAlts dt

$ map item alts

mapM_ ( \ (Construct c tc p sels) -> do

addOpId c (simpleTypeScheme $

getConstrType dt p tc)

[] (ConstructData i)

mapM_ ( \ (Select s ts pa) ->

addOpId s (simpleTypeScheme $

getSelType dt pa ts)

[] (SelectData [c] i)

) sels) newAlts

addTypeId (DatatypeDefn genKind [] newAlts) inst k i

anaPseudoType :: Maybe Kind -> TypeScheme -> State Env (Kind, TypeScheme)

anaPseudoType mk (TypeScheme tArgs (q :=> ty) p) =

do k <- case mk of

Nothing -> return star

Just j -> anaKindS j

tm <- gets typeMap -- save global variables

mapM_ anaTypeVarDecl tArgs

(sk, newTy) <- anaTypeS (k, ty)

let newPty = TypeScheme tArgs (q :=> newTy) p

newK = typeArgsListToKind tArgs sk

case mk of

Nothing -> return ()

Just j -> checkKindsS ty j newK

putTypeMap tm -- forget local variables

return (newK, newPty)

typeArgsListToKind :: [TypeArg] -> Kind -> Kind

typeArgsListToKind tArgs k =

if null tArgs then k

else typeArgsListToKind (init tArgs)

(KindAppl (typeArgToKind $ last tArgs) k [])

typeArgToKind :: TypeArg -> Kind

typeArgToKind (TypeArg _ k _ _) = k

anaTypeVarDecl :: TypeArg -> State Env ()

anaTypeVarDecl(TypeArg t k _ _) =

do nk <- anaKindS k

addTypeId TypeVarDefn Plain nk t

kindArity :: ApplMode -> Kind -> Int

kindArity m (KindAppl k1 k2 _) =

case m of

TopLevel -> kindArity OnlyArg k1 +

kindArity TopLevel k2

OnlyArg -> 1

kindArity m (ExtClass _ _ _) = case m of

TopLevel -> 0

OnlyArg -> 1

convertTypePatterns :: [TypePattern] -> Result [Id]

convertTypePatterns [] = Result [] $ Just []

convertTypePatterns (s:r) =

let Result d m = convertTypePattern s

Result ds (Just l) = convertTypePatterns r

in case m of

Nothing -> Result (d++ds) $ Just l

Just i -> Result (d++ds) $ Just (i:l)

convertTypePattern, makeMixTypeId :: TypePattern -> Result Id

convertTypePattern (TypePattern t _ _) = return t

convertTypePattern(TypePatternToken t) =

if isPlace t then fatal_error ("illegal type '__'") (tokPos t)

else return $ (simpleIdToId t)

convertTypePattern t =

if {- hasPlaces t && -} hasTypeArgs t then

fatal_error ( "arguments in type patterns not yet supported")

-- "illegal mix of '__' and '(...)'"

(posOfTypePattern t)

else makeMixTypeId t

-- TODO trailing places are not necessary for curried kinds

-- and should be ignored to avoid different Ids "Pred" and "Pred__"

typePatternToTokens :: TypePattern -> [Token]

typePatternToTokens (TypePattern ti _ _) = getTokenList place ti

typePatternToTokens (TypePatternToken t) = [t]

typePatternToTokens (MixfixTypePattern ts) = concatMap typePatternToTokens ts

typePatternToTokens (BracketTypePattern pk ts ps) =

let tts = map typePatternToTokens ts

expanded = concat $ expandPos (:[]) (getBrackets pk) tts ps in

case pk of

Parens -> if length tts == 1 &&

length (head tts) == 1 then head tts

else expanded

_ -> expanded

typePatternToTokens (TypePatternArg (TypeArg v _ _ _) _) =

[Token "__" (posOfId v)]

-- compound Ids not supported yet

getToken :: GenParser Token st Token

getToken = token tokStr tokPos Just

parseTypePatternId :: GenParser Token st Id

parseTypePatternId =

do ts <- many1 getToken

return $ Id ts [] []

makeMixTypeId t =

case parse parseTypePatternId "" (typePatternToTokens t) of

Left err -> fatal_error (showErrorMessages "or" "unknown parse error"

"expecting" "unexpected" "end of input"

(errorMessages err))

(errorPos err)

Right x -> return x

hasPlaces, hasTypeArgs :: TypePattern -> Bool

hasPlaces (TypePattern _ _ _) = False

hasPlaces (TypePatternToken t) = isPlace t

hasPlaces (MixfixTypePattern ts) = any hasPlaces ts

hasPlaces (BracketTypePattern _ ts _) = any hasPlaces ts

hasPlaces (TypePatternArg _ _) = False

hasTypeArgs (TypePattern _ _ _) = True

hasTypeArgs (TypePatternToken _) = False

hasTypeArgs (MixfixTypePattern ts) = any hasTypeArgs ts

hasTypeArgs (BracketTypePattern _ ts _) = any hasTypeArgs ts

hasTypeArgs (TypePatternArg _ _) = True

-- ---------------------------------------------------------------------------

-- for storing selectors and constructors

-- ---------------------------------------------------------------------------

-- | store assumptions

putAssumps :: Assumps -> State Env ()

putAssumps as = do { e <- get; put e { assumps = as } }

unifiable :: TypeScheme -> TypeScheme -> State Env Bool

unifiable sc1 sc2 =

do tm <- gets typeMap

c <- gets counter

let Result ds mm = evalState (unifIable tm sc1 sc2) c

appendDiags ds

return $ isJust mm

-- | storing an operation

addOpId :: UninstOpId -> TypeScheme -> [OpAttr] -> OpDefn -> State Env ()

addOpId i sc attrs defn =

do as <- gets assumps

let l = Map.findWithDefault [] i as

if sc `elem` map opType l then

addDiag $ mkDiag Warning

"repeated value" i

else do bs <- mapM (unifiable sc) $ map opType l

if or bs then addDiag $ mkDiag Error

"illegal overloading of" i

else putAssumps $ Map.insert i

(OpInfo sc attrs defn : l ) as