If I have a function

fun <T, R> Optional<T>.mapDefault(default: R, mapper: (T) -> R): R

and call it with a default of a subtype of a

sealed class

e.g.

maybeThing.mapDefault(Action.NoFoo) { thing -> Action.Foo }

then this fails type checking because

R

in

mapDefault

is bound to

Action.NoFoo

— is there a good way around this besides calling

maybeThing.mapDefault<Thing, Action>

?

Introduce a generic super type.

wow, niiiice