Challenge 1: Applying a Wrapped Function With <*> — Possible Solution
====================================================================

Main.hs:

main :: IO ()
main = do
  print (Just (*2) <*> Just 10)
  print (Nothing <*> Just 10 :: Maybe Int)

Output:

    Just 20
    Nothing

Explanation:
Just (*2) <*> Just 10 has BOTH the function and the value wrapped in
Just -- exactly the case fmap alone can't handle. <*> unwraps the
function from the first Just, unwraps the value from the second, and
applies one to the other, rewrapping the result as Just 20. When the
function side is Nothing instead, there is no function to apply at
all -- <*> short-circuits immediately to Nothing, the same "safely
does nothing" behavior fmap showed for a Nothing VALUE in the
previous chapter, just now on the function side instead.

WHY THIS WORKS AS AN ANSWER
------------------------------
This demonstrates <*> with both a genuinely successful case (wrapped
function, wrapped value, both Just) and the Nothing-short-circuits
case, covering both real behaviors the chapter's own Just (+3) <*>
Just 5 example implies but doesn't show explicitly.