val listOfNumbers = "text 123 and more text 456".someKindOfMap { Regex("\\d+") }

val handler: Handler = { req, res -> res.body("Hello") }

val tuple = "key=value".split("=")
val pair =  when {
                  tuple.size > 1 -> tuple[0] to tuple[1]
                  else -> tuple[0] to ""
               }

@FunctionalInterface
public interface ErrorHandler {
    void handle(Request request, Response response);
}

typealias ErrorHandler = (request : Request, response : Response) -> Unit

error(500, (req, res) -> {
    // return type expected
});

private var disposable: CompositeDisposable = CompositeDisposable()

private lateinit var disposable: CompositeDisposable

    init {
        disposable = CompositeDisposable()
    }

\d

Do you have incremental builds enabled?

fun <T1 : Any, T2 : Any, T3 : Any, T4: Any, T5: Any, R: Any> safeLet(p1: T1?, p2: T2?, p3: T3, p4: T4, p5:T5, block: (T1, T2, T3, T4, T5) -> R?): R? {
    return if (p1 != null && p2 != null && p3 != null && p4 != null && p5 != null) block(p1, p2, p3, p4, p5) else null
}

ORDER BY name ASC, age DESC

persons.sortedBy { it.name }.sortedByDescending { it.age }

rects.sortWith(Comparator { a, b -> ... })

Comparator

Kotlin = everyone must switch to Idea

invoke()

class SomeAction : ()->?!?!? {
    override fun invoke <T> (): T {
        return ...
    }
}

null as Node?