import qualified Data.List as List
import Data.Monoid (Monoid(..))
import Data.Typeable
+import Data.Foldable (Foldable(foldMap))
{-
-- just for testing
mappend = union
mconcat = unions
+instance Foldable Set where
+ foldMap f Tip = mempty
+ foldMap f (Bin _s k l r) = foldMap f l `mappend` f k `mappend` foldMap f r
+
#if __GLASGOW_HASKELL__
{--------------------------------------------------------------------