How do I read two numbers from an inputbox in Haskell online with getLine > > =
g::Float -> Float -> Float
g n t = 2 - (n*t**2+3))
main = getLine >>= (\n -> putStrLn(show (g (read n :: String -> Float))))
g >>= (\t -> putStrLn(show (g (read t :: String -> Float))))
It is more convenient to use the block of than to write the operation based on the operator bind >>= as it seems you are trying to do.
Likewise, take advantage of the compiler's ability to choose the type of polymorphic operation as with those used to read or write in a console.
I think you're looking for something like this:
g :: Float -> Float -> Float
g n t = 2 - (n*t**2+3)
main :: IO ()
main =
do
x <- getLine
y <- getLine
print $ g (read x) (read y)
Both x and y are Strings . Since invoking the function g waits two Floats , the compiler knows that it has to use the function read of the instance of the class Read Float .
Note : I do not know what haskell online you are using, nor what is the inputbox .
Edited : if you want to show the result with a warning:
main :: IO ()
main =
do
x <- getLine
y <- getLine
putStr "El resultado es "
print $ g (read x) (read y)
If that's not enough, you can convert the result to String with the function show
main :: IO ()
main =
do
x <- getLine
y <- getLine
let res = g (read x) (read y)
putStrLn ("El resultado es " ++ show res)