Union types

Language Design
10

Working proof of concept, just for fun :

 
public class Test {
    public fun doSomething(el: JsonElement) {
    }
}

public class JsonFunction<T, R>(private val self: T, private val method: T.(JsonElement) -> R) {

  public operator fun invoke(arg: Boolean) = self.method(JsonPrimitive(arg))

  public operator fun invoke(arg: Number) = self.method(JsonPrimitive(arg))

  public operator fun invoke(arg: String) = self.method(JsonPrimitive(arg))

  public operator fun invoke(arg: Char) = self.method(JsonPrimitive(arg))

  public operator fun invoke(arg: JsonElement) = self.method(arg)

}


public val Test.doSomethingAuto: JsonFunction<Test, Unit> get() = JsonFunction(this) { doSomething(it) }



public fun main() {

  Test().doSomethingAuto(42)

  Test().doSomethingAuto(“Hello, world”)

}