Union types

[Dmitry_Petrov_1]

@jrudolph

Another use case here: I’d especially want to use discriminated unions for single case types, which effectively allows me to e.g. have two incompatible strings.

You can use sealed classes for discriminated unions.

Note also that union types are a slightly different thing: a union type A | B is compatible with both A and B (with a run-time check). A discriminated union type is not, it requires an explicit constructor and explicit destructuring. They also would be mapped differently on JVM.