BoundedBy.hs

-- | When dealing with multiple sets, you can have different
-- constraints. This can be observed in Mahjong where Suits will have
-- nine different values, but honors will vary. Wind and Dragon for
-- example have four and three values respectfully. They also don't
-- fit in with Bounded because these concepts exist together at the
-- same time and need to be handled differently. In many circumstances
-- you can define `minBoundBy` and `maxBoundBy` as just `minBound` and
-- `maxBound`.
class Bounded b => BoundedBy a b where
  minBoundBy :: a -> b
  minBoundBy _ = minBound

  maxBoundBy :: a -> b
  maxBoundBy _ = maxBound

data Suits = Character
           | Circle
           | Bamboo
           deriving (Eq, Show)

instance BoundedBy Suits SNum

data SNum = One
          | Two
          | Three
          | Four
          | Five
          | Six
          | Seven
          | Eight
          | Nine
          deriving (Eq, Ord, Enum, Bounded, Show)

test_minBoundBy :: Suits -> SNum
test_minBoundBy = minBoundBy