Hello, I have a result-pattern-like generic sealed...

# getting-started

[gabrielfv]

Hello, I have a result-pattern-like generic sealed class, I'd like to define objects that represent possible values that are independent of the type specified, is it possible?

sealed class State<out T : Any>
object Loading : State</* Type isn't relevant here */>()
data class Loaded<T : Any>(data: T) : State<T>()

There's no reason for Loading not to be an object in this context, neither is there any reason for it to specify a type. Changing the variance to contravariance and making it an Any is a design flaw in this scenario. Is there any convenient alternative to what I'm trying to accomplish here?

[StavFX]

object Loading : State<Nothing>()

?

[gabrielfv]

That did work. Didn't cross my mind Nothing was a possibility

[StavFX]

Yeah, there’s no Java equivalent to Nothing, so I tend to forget about it too, but it’s really useful sometimes

[Matteo Mirk]

Yes, that’s the correct usage of Nothing ! It works because it’s a subtype of any type (the opposite of Any) but can’t be instantiated.

[gabrielfv]

The beauty of a good type system