takeEven n xs =
  (L.drop n . L.take (2 * n) $ xs) L.++ (takeEven n . L.drop (2 * n) $ xs)
takeEven n xs =
  (L.drop n . L.take (2 * n) $ xs) L.++ (takeEven n . L.drop (2 * n) $ xs)
takeEven n xs =
  (L.drop n . L.take (2 * n) $ xs) L.++ (takeEven n . L.drop (2 * n) $ xs)