import Data.Char

--Main Funktion
function :: [String] -> (Int -> Int) -> [Int]
function [] _ = []
function (x:xs) f | "old" `sublist` x = f (getInt x) : function xs f
             | "new" `sublist` x = getInt x : function xs f
    where
        sublist :: String -> String -> Bool
        sublist xs@(x:s) (y:s') = if x == y then sublist s s' || sublist xs s' else sublist xs s'
        sublist [] _ = True
        sublist _ [] = False

        getInt :: String -> Int
        getInt xs = calcVal $ getIntList xs

        calcVal :: [Int] -> Int
        calcVal [] = 0
        calcVal (x:xs) = x * 10^(length xs) + calcVal xs

        getIntList :: String -> [Int]
        getIntList [] = []
        getIntList (x:xs) = if isDigit x then digitToInt x : getIntList xs else getIntList xs


--TestWerte
chaos =["old price: 40", "new price: 21", "old price: 29", "old price: 50", "new price: 101"]

discount :: Int -> Int
discount x
    | x <= 20 = (x * 8) `div` 10
    | x <= 50 =  (x * 6) `div` 10
    | otherwise = (x * 4) `div` 10