comando para executarTerminalCMD

import System.IO

main = do
 hSetBuffering stdout NoBuffering
 putStr "a = "
 a <- getLine
 putStr "b = "
 b <- getLine
 putStrLn $ "a+b = "++ a ++ "+" ++ b ++ "=" ++show((read a :: Double)+(read b::Double))
 x <- getChar
 putStrLn ""