import kotlin.test.assertEquals inline fun foo(x : R, y : R, block : (R) -> T) : T { val a = x is Number val b = x is Object val b1 = x as Object if (a && b) { return block(x) } else { return block(y) } } fun box() : String { assertEquals(1, foo(1, 2) { x -> x as Int }) assertEquals("def", foo("abc", "def") { x -> x as String }) return "OK" }