Why this is not allowed? ```public value class Set...

# language-evolution

[Tomasz Krakowiak]

Why this is not allowed?

public value class SetValue<Value>(public val value : Value)

"Inline class cannot have value parameter of type 'Value'"
Thread in Slack Conversation

[Tomasz Krakowiak]

Sorry, for cross-posting, but I'm still looking for an answer. Probably there's good reason for that, but if not - That's a real use-case. I'm writing store API and this represents operation for the simplest Property store.

[Rob Elliot]

Why is Value a generic type?

[Tomasz Krakowiak]

@Rob Elliot Because SetValue represents operation on a Property<Value> store, that is itself generic.

[Tomasz Krakowiak]

public interface Store<out State, in Mutation> {
    public fun <Value> query(query : Query<State, Value>) : Value
    public fun apply(mutation : Mutation)
    // ...
}

.

public class PropertyStore<Value> : Store<Value, SetValue<Value>>

[Roukanken]

wierd thing is, if you change the parameter type to smth like List<Value> it works 🤔

[Roukanken]

found this related to it: https://youtrack.jetbrains.com/issue/KT-26352
seems like it's unclear what such class should do, therefore it's not allowed