Identity class and Monad instance

[NathanHowell]

Having Identity around is useful for those of us writing Applicative and Monad heavy code.

[johnynek]

Thanks!

[jnievelt]

Curious why Monad.option doesn't suffice here. Seems like it would only handle null differently?

[NathanHowell]

@jnievelt Monad.some is equivalent, Monad.option isn't due to null handling and returning an Option that needs to be pattern matched. Identity is the common name in Haskell (and scalaz) and perhaps more obvious in intent.