```fun <T: Any?> a(b: (value: T) -> Unit)...

# getting-started

[maxmello]

fun <T: Any?> a(b: (value: T) -> Unit) {
    b(null)
}

why does this not work? Why does it say T is non-nullable, even though it uses Any? ? Can I make this work without changing the lambda param to value: T??

[ephemient]

T : Any? includes T : Any. if you want to always allow null, you need T? (so changing the type of your lambda, yes)

[maxmello]

Oh you are right now I get it, thank you 😅

[Sam]

Maybe you’re expecting it to work more like a List<T>, but remember that list elements have out variance whereas function parameters have in variance. So a List<T> is a List<T?>, but a (T) -> Unit is not a (T?) -> Unit.