But if you implemented Maybe in Java, there still wouldn't be any compile-time guarantee that Nothing would be handled, right? At best you'd have something in c

But if you implemented Maybe in Java, there still wouldn't be any compile-time guarantee that Nothing would be handled, right? At best you'd have something in code that more strongly encourages a certain convention. Just now I briefly looked at implementations of Maybe in Java and at least one of them fakes this with checked exceptions, while another seems to lean heavily on Guava's Function interface, which is just awkward to use. I'd certainly be interested in seeing alternative implementations, if you know of any that are decent. Also, a maybe more serious issue is that since it's not idiomatic Java you'd have to do a lot of wrapping around libraries, and hard-selling to colleagues. Admittedly no longer dealing with flaws in Java's type system, but a big part of a language is the community and ecosystem, and in Haskell's case people using it have already bought on to the advantages of stronger types.