botva.hs

{-#LANGUAGE ScopedTypeVariables#-}

import Text.Read
import System.IO

prompt :: String -> IO String
prompt text = do
  putStr text
  hFlush stdout
  getLine

maybePrompt :: (Read a) => String -> IO (Maybe a)
maybePrompt text = fmap readMaybe $ prompt text

rateHours :: Float -> Float -> Float
rateHours hours rate = if hours > 40
  then (hours - 40) * rate * 1.5 + 40 * rate
  else hours * rate

main :: IO ()
main = do
  maybeHours :: Maybe Float <- maybePrompt "Enter hours: "
  case maybeHours of
    Just hours -> do
      maybeRate :: Maybe Float <- maybePrompt "Enter rate: "
      case maybeRate of
        Just rate -> putStrLn $ show $ rateHours rate hours
        Nothing -> putStrLn "Rate must be float"
    Nothing -> putStrLn "Hours must be float"