Вычислительная программа с пользовательским вводом

calc:: Double -> Double -> Double -> Double -> (Double,Double,Double)
calc length' height width weight =
    let volume=length' * height * width
    in (weight, volume, weight / volume)
    
main :: IO () 
main = print $ calc 0.4 0.25 0.3 1.5

import System.IO
 
calc:: Double -> Double -> Double -> Double -> (Double,Double,Double)
calc length' height width weight =
    let volume=length' * height * width
    in (weight, volume, weight / volume)
    
main :: IO () 
main = do
       putStr "l="
       hFlush stdout
       sl <- getLine
       putStr "h="
       hFlush stdout
       sh <- getLine
       putStr "w="
       hFlush stdout
       sw <- getLine
       putStr "p="
       hFlush stdout
       sp <- getLine
       print $ calc (read sl :: Double) (read sh :: Double) (read sw :: Double) (read sp :: Double)

module Main where
 
import System.IO
 
-- Следующие 2 строки нужны только для ghc версий ниже 7.10
import Control.Monad
import Control.Applicative
 
calc:: Double -> Double -> Double -> Double -> (Double,Double,Double)
calc length' height width weight =
    let volume=length' * height * width
    in (weight, volume, weight / volume)
 
ask :: String -> IO Double
ask prompt = putStr prompt >> readLn
    
main :: IO () 
main = do
    hSetBuffering stdout NoBuffering
    (weight, volume, density) <- calc <$> 
        (ask "Length ? ") <*>
        (ask "Height ? ") <*>
        (ask "Width ? ") <*>
        (ask "Weight ? ") 
    putStrLn $ "Weight=" ++ (show weight) ++ 
               ", Volume=" ++ (show volume) ++
               ", Density=" ++ (show density)

putStrLn $ "Weight=" ++ (show weight) ++ 
               ", Volume=" ++ (show volume) ++
               ", Density=" ++ (show density)