There are many things you can express with ADTs that you can't express with nullable types, and once you have those, Option is simpler than extending the type s

There are many things you can express with ADTs that you can't express with nullable types, and once you have those, Option is simpler than extending the type system. EDIT: Another thing you can do with Option is define generic abstractions that work on it and other types, like map/flatMap. This in turn means you can write generic functions over anything that can be flatMapped which work automatically for Options. (I don't know if there's anything equivalent in Kotlin though?)