Bounded型クラス

上限と下限を持つ

e.g. Int(固定調整数)

code:hs

class Bounded a where

minBound, maxBound :: a

例

code:hs

instance Bounded Bool where

minBound = False

maxBound = True

code:hs

data Bearing = North | East | South | West deriving (Bounded)

以下と同じ

code:hs

data Bearing = North | East | South | West

instance Bounded Bearing where

minBound = North

maxBound = West

ほんま？