Hi there! I've seen that with 1.4 SAM intefaces are now converted properly between Kotlin and Java. This is great, but there is a problem, however: I still can't define functions that return void. For example if I have a signature like this:

fun someFun(fn: (SomeClass) -> Unit)

I have to explicitly return

Unit.INSTANCE

from Java code. Is there a way to fix this (besides writing a helper function)

Try returning Nothing

Kotlin has a single

interface Function<out R>

type so as far as Java is concerned, you always need to return some value for

R

. for the sake of interop, you could define your own SAM or use Java's specialized SAMs returning void, e.g.

fun someFun(fn: Consumer<SomeClass>)

Thanks.