{-# OPTIONS -fglasgow-exts #-}
import Data.Generics.Basics
import Data.Generics.Aliases
import Data.Generics.Twins(gzipWithQ)
{-
-- | Twin map for queries
gzipWithQ :: GenericQ (GenericQ r) -> GenericQ (GenericQ [r])
gzipWithQ f x y = case gmapAccumQ perkid funs y of
                   ([], r) -> r
                   _       -> error "gzipWithQ" 
 where
  perkid a d = (tail a, unGQ (head a) d)
  funs = gmapQ (\k -> GQ (f k)) x
-}
-- | Generic equality: an alternative to \"deriving Eq\"
geq :: Data a => a -> a -> Bool
geq x y = geq' x y
  where
    geq' :: forall a b. (Data a, Data b) => a -> b -> Bool
    geq' x y =     (toConstr x == toConstr y)
                && and (gzipWithQ geq' x y)