    {-|
        For deriving Data on abstract data types.
    -}
    module Data.Derive.DataAbstract(makeDataAbstract) where
    {-
    import Data.Data(Data(..))

    example :: Custom

    instance Typeable a => Data (Sample a) where
        gfoldl k r x = r x
        gunfold = error "Data.gunfold not implemented on abstract data type: Sample"
        toConstr = error "Data.gunfold not implemented on abstract data type: Sample"
        dataTypeOf = error "Data.gunfold not implemented on abstract data type: Sample"

    -}

    import Data.Derive.DSL.HSE

    -- GENERATED START

    import Data.Derive.DSL.DSL
    import Data.Derive.Internal.Derivation

    makeDataAbstract :: Derivation
    makeDataAbstract = derivationCustomDSL "DataAbstract" custom $
        List [Instance ["Typeable"] "Data" (List [App "InsDecl" (List [App
        "FunBind" (List [List [App "Match" (List [App "Ident" (List [
        String "gfoldl"]),List [App "PVar" (List [App "Ident" (List [
        String "k"])]),App "PVar" (List [App "Ident" (List [String "r"])])
        ,App "PVar" (List [App "Ident" (List [String "x"])])],App
        "Nothing" (List []),App "UnGuardedRhs" (List [App "App" (List [App
        "Var" (List [App "UnQual" (List [App "Ident" (List [String "r"])])
        ]),App "Var" (List [App "UnQual" (List [App "Ident" (List [String
        "x"])])])])]),App "BDecls" (List [List []])])]])]),App "InsDecl" (
        List [App "PatBind" (List [App "PVar" (List [App "Ident" (List [
        String "gunfold"])]),App "Nothing" (List []),App "UnGuardedRhs" (
        List [App "App" (List [App "Var" (List [App "UnQual" (List [App
        "Ident" (List [String "error"])])]),App "Lit" (List [App "String"
        (List [Concat (List [String
        "Data.gunfold not implemented on abstract data type: ",DataName])]
        )])])]),App "BDecls" (List [List []])])]),App "InsDecl" (List [App
        "PatBind" (List [App "PVar" (List [App "Ident" (List [String
        "toConstr"])]),App "Nothing" (List []),App "UnGuardedRhs" (List [
        App "App" (List [App "Var" (List [App "UnQual" (List [App "Ident"
        (List [String "error"])])]),App "Lit" (List [App "String" (List [
        Concat (List [String
        "Data.gunfold not implemented on abstract data type: ",DataName])]
        )])])]),App "BDecls" (List [List []])])]),App "InsDecl" (List [App
        "PatBind" (List [App "PVar" (List [App "Ident" (List [String
        "dataTypeOf"])]),App "Nothing" (List []),App "UnGuardedRhs" (List
        [App "App" (List [App "Var" (List [App "UnQual" (List [App "Ident"
        (List [String "error"])])]),App "Lit" (List [App "String" (List [
        Concat (List [String
        "Data.gunfold not implemented on abstract data type: ",DataName])]
        )])])]),App "BDecls" (List [List []])])])])]
    -- GENERATED STOP

    custom = customContext context

    context :: FullDataDecl -> Context -> Context
    context d _ = [ClassA (qname t) [tyVar x] | x <- dataDeclVars $ snd d, t <- ["Typeable","Data"]]