There's also no compiletime guarantee that Nothing is handled in Haskell; there are plenty of unsafe partial functions. In a non-total language, you unfortunate

There's also no compiletime guarantee that Nothing is handled in Haskell; there are plenty of unsafe partial functions. In a non-total language, you unfortunately have to avoid partial functions without help from the compiler. You're quite right that programming with these kinds of types in Java introduces you to a whole new kind of Hell! I'm not sure I'd recommend it. However, I'm simply pointing out that types like these are _not_ language features. Some languages may be better suited to them than others, but they are definitely library features, and had best not be considered otherwise.