Maximum possible score in first row of Yahtzee

yahtzee.hs

module Yahtzee where

import Data.List (group, maximumBy, sortBy)

yahtzee_upper :: [Int] -> Int
yahtzee_upper numbers =
  sum
    . maximumBy (\x x' -> compare (sum x) (sum x'))
    . group
    . sortBy (compare)
    $ numbers

main :: IO ()
main =
  print $ yahtzee_upper [4, 5, 4, 3, 3]