You can think of Nothing and Just as functions that construct a MaybeInteger. Nothing takes no parameters because there's no value there, so why would it? Jus

You can think of Nothing and Just as functions that construct a MaybeInteger. Nothing takes no parameters because there's no value there, so why would it? Just takes an integer and gives you a MaybeInteger containing the integer you supplied to it. There is only a single type here, namely MaybeInteger.