public @interface val

Use val as the type of any local variable declaration (even in a for-each statement), and the type will be inferred from the initializing expression. For example: val x = 10.0; will infer double, and val y = new ArrayList<String>(); will infer ArrayList<String>. The local variable will also be made final. Note that this is an interface because val x = 10; will be desugared to @val int x = 10;