女性客の年齢分布.hs

import Data.List



data Sex = Male | Female deriving (Show, Eq, Ord)
data Customer = Customer{ sex :: Sex, age :: Int }  deriving(Show, Eq, Ord)

(|>) :: a -> (a -> b) -> b
x |> f = f x


main = do
  let customers = [Customer Female 24,
                    Customer Male 23,
                    Customer Female 28,
                    Customer Female 59,
                    Customer Female 12,
                    Customer Female 24,
                    Customer Female 59,
                    Customer Male 59
                  ]
  putStrLn . show $ customers
                    |> filter (\c -> sex c == Female)
                    |> sortBy (\c n -> compare  (age c) (age n))
                    |> groupBy (==)