{-# LANGUAGE EmptyDataDecls, FlexibleContexts
  , FlexibleInstances, MultiParamTypeClasses, ScopedTypeVariables
  , TemplateHaskell, UndecidableInstances #-}
{-# OPTIONS -Wall -fno-warn-missing-signatures #-}

module SYBInstances

where

import Graphics.UI.SybWidget.MySYB hiding (NoCtx, noCtx)

data Tree a = Tree (Tree a) (Tree a)
            | Leaf a deriving (Show, Eq)
data Eternal = Eternal (Eternal)

data ThreeProd a b c = ThreeProd { one :: a, two :: b, three :: c }

-- |The context for generic autoform
data NoCtx a

noCtx :: Proxy NoCtx
noCtx = error "noCtx"

isTree :: Tree a -> Bool
isTree (Leaf _)   = False
isTree (Tree _ _) = True

-- |Instantiation of the Sat class
instance Sat (NoCtx a)

$(derive [''Tree, ''Eternal, ''ThreeProd])