This is to document a small, working example of how applicative functors can be used in Haskell.

import Control.Applicative

f1:: Int -> Int -> Int
f1 x y = 2*x+y

main = do return $ show $ f1 <$> (Just 1) <*> (Just 2)

A very short explanation follows.

On line 1, the necessary base library module is imported

On lines 3 and 4, a small function from two integers to one integer is defined

On line 6, it is shown, how the applicative functors are used to apply the function on Maybe- values.