Parametric Polymorphism example over tiles

TilesParametricPolymorphism.hs

module TilesParametricPolymorphism where

class Tile a where
  over :: a -> a

instance Tile (Dora Character) where
  over MultiSet (Dora Character) -> undefined
  
instance Tile (Dora Circle) where
  over MultiSet (Dora Circle) -> undefined
  
instance Tile (Dora Bamboo) where
  over MultiSet (Dora Bamboo) -> undefined

instance Tile (Dora Wind) where
  over MultiSet (Dora Wind) -> undefined

instance Tile (Dora Dragon) where
  over MultiSet (Dora Dragon) -> undefined

over :: Hand -> Hand
over h = h { characters = over (characters h)
           , circles    = over (circles h)
           , bamboo     = over (bamboo h)
           , wind       = over (wind h)
           , dragon     = over (dragon h)
           }