    module Data.Derive.Data(makeData) where
    {-
    import Data.Data

    example :: Custom

    instance (Data a, Typeable a) => Data (Sample a) where
        gfoldl k r (First) = r First
        gfoldl k r (Second x1 x2) = r Second `k` x1 `k` x2
        gfoldl k r (Third x1) = r Third `k` x1

        gunfold k z c = case constrIndex c - 1 of
            0 -> z First
            1 -> const k 1 $ const k 2 $ z Second
            2 -> const k 1 $ z Third
            i -> error $ ("Data.gunfold for Sample" ++ ", unknown index: ") ++ show i

        toConstr x@First{}  = indexConstr (dataTypeOf x) (0+1)
        toConstr x@Second{} = indexConstr (dataTypeOf x) (1+1)
        toConstr x@Third{}  = indexConstr (dataTypeOf x) (2+1)

        dataTypeOf _ = ty
            where ty = mkDataType $(dataName)
                       [mkConstr ty "First"  $(ctorFields 0) $(ctorFixity 0)
                       ,mkConstr ty "Second" $(ctorFields 1) $(ctorFixity 1)
                       ,mkConstr ty "Third"  $(ctorFields 2) $(ctorFixity 2)]

    test :: Computer

    instance Data Computer where
        gfoldl k r (Laptop x1 x2) = r Laptop `k` x1 `k` x2
        gfoldl k r (Desktop x1) = r Desktop `k` x1
        gunfold k z c = case constrIndex c - 1 of
            0 -> k $ k $ z Laptop
            1 -> k $ z Desktop
            i -> error $ "Data.gunfold for Computer, unknown index: " ++ show i
        toConstr x@Laptop{} = indexConstr (dataTypeOf x) 1
        toConstr x@Desktop{} = indexConstr (dataTypeOf x) 2
        dataTypeOf _ = ty
          where ty = mkDataType "Example.Computer"
                     [mkConstr ty "Laptop" ["weight", "speed"] Prefix
                     ,mkConstr ty "Desktop" ["speed"] Prefix]

    -}

    import Data.Derive.DSL.HSE
    import qualified Language.Haskell as H

    -- GENERATED START

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

    makeData :: Derivation
    makeData = derivationCustomDSL "Data" custom $
        List [Instance ["Data","Typeable"] "Data" (List [App "InsDecl" (
        List [App "FunBind" (List [MapCtor (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 "PParen" (List [App "PApp" (List [App "UnQual" (List [App
        "Ident" (List [CtorName])]),MapField (App "PVar" (List [App
        "Ident" (List [Concat (List [String "x",ShowInt FieldIndex])])]))]
        )])],App "Nothing" (List []),App "UnGuardedRhs" (List [Fold (App
        "InfixApp" (List [Tail,App "QVarOp" (List [App "UnQual" (List [App
        "Ident" (List [String "k"])])]),Head])) (Concat (List [Reverse (
        MapField (App "Var" (List [App "UnQual" (List [App "Ident" (List [
        Concat (List [String "x",ShowInt FieldIndex])])])]))),List [App
        "App" (List [App "Var" (List [App "UnQual" (List [App "Ident" (
        List [String "r"])])]),App "Con" (List [App "UnQual" (List [App
        "Ident" (List [CtorName])])])])]]))]),App "BDecls" (List [List []]
        )]))])]),App "InsDecl" (List [App "FunBind" (List [List [App
        "Match" (List [App "Ident" (List [String "gunfold"]),List [App
        "PVar" (List [App "Ident" (List [String "k"])]),App "PVar" (List [
        App "Ident" (List [String "z"])]),App "PVar" (List [App "Ident" (
        List [String "c"])])],App "Nothing" (List []),App "UnGuardedRhs" (
        List [App "Case" (List [App "InfixApp" (List [App "App" (List [App
        "Var" (List [App "UnQual" (List [App "Ident" (List [String
        "constrIndex"])])]),App "Var" (List [App "UnQual" (List [App
        "Ident" (List [String "c"])])])]),App "QVarOp" (List [App "UnQual"
        (List [App "Symbol" (List [String "-"])])]),App "Lit" (List [App
        "Int" (List [Int 1])])]),Concat (List [MapCtor (App "Alt" (List [
        App "PLit" (List [App "Int" (List [CtorIndex])]),App
        "UnGuardedAlt" (List [Fold (App "InfixApp" (List [Head,App
        "QVarOp" (List [App "UnQual" (List [App "Symbol" (List [String "$"
        ])])]),Tail])) (Concat (List [MapField (Application (List [App
        "Var" (List [App "UnQual" (List [App "Ident" (List [String "const"
        ])])]),App "Var" (List [App "UnQual" (List [App "Ident" (List [
        String "k"])])]),App "Lit" (List [App "Int" (List [FieldIndex])])]
        )),List [App "App" (List [App "Var" (List [App "UnQual" (List [App
        "Ident" (List [String "z"])])]),App "Con" (List [App "UnQual" (
        List [App "Ident" (List [CtorName])])])])]]))]),App "BDecls" (List
        [List []])])),List [App "Alt" (List [App "PVar" (List [App "Ident"
        (List [String "i"])]),App "UnGuardedAlt" (List [App "InfixApp" (
        List [App "Var" (List [App "UnQual" (List [App "Ident" (List [
        String "error"])])]),App "QVarOp" (List [App "UnQual" (List [App
        "Symbol" (List [String "$"])])]),App "InfixApp" (List [App "Paren"
        (List [App "InfixApp" (List [App "Lit" (List [App "String" (List [
        Concat (List [String "Data.gunfold for ",DataName])])]),App
        "QVarOp" (List [App "UnQual" (List [App "Symbol" (List [String
        "++"])])]),App "Lit" (List [App "String" (List [String
        ", unknown index: "])])])]),App "QVarOp" (List [App "UnQual" (List
        [App "Symbol" (List [String "++"])])]),App "App" (List [App "Var"
        (List [App "UnQual" (List [App "Ident" (List [String "show"])])]),
        App "Var" (List [App "UnQual" (List [App "Ident" (List [String "i"
        ])])])])])])]),App "BDecls" (List [List []])])]])])]),App "BDecls"
        (List [List []])])]])]),App "InsDecl" (List [App "FunBind" (List [
        MapCtor (App "Match" (List [App "Ident" (List [String "toConstr"])
        ,List [App "PAsPat" (List [App "Ident" (List [String "x"]),App
        "PRec" (List [App "UnQual" (List [App "Ident" (List [CtorName])]),
        List []])])],App "Nothing" (List []),App "UnGuardedRhs" (List [
        Application (List [App "Var" (List [App "UnQual" (List [App
        "Ident" (List [String "indexConstr"])])]),App "Paren" (List [App
        "App" (List [App "Var" (List [App "UnQual" (List [App "Ident" (
        List [String "dataTypeOf"])])]),App "Var" (List [App "UnQual" (
        List [App "Ident" (List [String "x"])])])])]),App "Paren" (List [
        App "InfixApp" (List [App "Lit" (List [App "Int" (List [CtorIndex]
        )]),App "QVarOp" (List [App "UnQual" (List [App "Symbol" (List [
        String "+"])])]),App "Lit" (List [App "Int" (List [Int 1])])])])])
        ]),App "BDecls" (List [List []])]))])]),App "InsDecl" (List [App
        "FunBind" (List [List [App "Match" (List [App "Ident" (List [
        String "dataTypeOf"]),List [App "PWildCard" (List [])],App
        "Nothing" (List []),App "UnGuardedRhs" (List [App "Var" (List [App
        "UnQual" (List [App "Ident" (List [String "ty"])])])]),App
        "BDecls" (List [List [App "PatBind" (List [App "PVar" (List [App
        "Ident" (List [String "ty"])]),App "Nothing" (List []),App
        "UnGuardedRhs" (List [Application (List [App "Var" (List [App
        "UnQual" (List [App "Ident" (List [String "mkDataType"])])]),App
        "SpliceExp" (List [App "ParenSplice" (List [App "Var" (List [App
        "UnQual" (List [App "Ident" (List [String "dataName"])])])])]),App
        "List" (List [MapCtor (Application (List [App "Var" (List [App
        "UnQual" (List [App "Ident" (List [String "mkConstr"])])]),App
        "Var" (List [App "UnQual" (List [App "Ident" (List [String "ty"])]
        )]),App "Lit" (List [App "String" (List [CtorName])]),App
        "SpliceExp" (List [App "ParenSplice" (List [App "App" (List [App
        "Var" (List [App "UnQual" (List [App "Ident" (List [String
        "ctorFields"])])]),App "Lit" (List [App "Int" (List [CtorIndex])])
        ])])]),App "SpliceExp" (List [App "ParenSplice" (List [App "App" (
        List [App "Var" (List [App "UnQual" (List [App "Ident" (List [
        String "ctorFixity"])])]),App "Lit" (List [App "Int" (List [
        CtorIndex])])])])])]))])])]),App "BDecls" (List [List []])])]])])]
        ])])])]
    -- GENERATED STOP

    custom d = customContext context d . customSplice splice d

    splice :: FullDataDecl -> Exp -> Exp
    splice d x | x ~= "dataName" = H.Lit $ H.String $ prettyPrint (fst d) ++ "." ++ dataDeclName (snd d)
    splice d (H.App x (H.Lit (H.Int y)))
        | x ~= "ctorFields" = H.List $ [H.Lit $ H.String a | (a,_) <- ctorDeclFields ctor, a /= ""]
        | x ~= "ctorFixity" = Con (UnQual (Ident "Prefix"))
        where ctor = dataDeclCtors (snd d) !! fromInteger y

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