var and passing to methods

gistfile1.txt

package example;

public class Example {

    public static void main(String... args) {
        var duck = (Quacks & Waddles) Mixin::create;

        // this works as the intersection type is inferred.
        methodThatDoesDucklikeThings(duck);

        var ducklikeException = new RuntimeException("runtime ex with message") {
            void quack() {
                System.out.println("Quack");
            }
            void waddle() {
                System.out.println("Waddle");
            }
        };

        // this works as Throwable is a supertype
        log(ducklikeException);

        // this would not work as the bounds don't match
//      methodThatDoesDucklikeThings(ducklikeException);


        // this does work as Quack is structurally equivalent to the method reference
        quack(ducklikeException::quack);
        // as does quacking an actual duck
        quack(duck);

    }

    static <T extends Quacks & Waddles> void methodThatDoesDucklikeThings(T ducklike) {
        ducklike.quack();
        ducklike.waddle();
    }

    static <T extends Throwable> void log(T t) {
        System.out.println(t.getMessage());
    }

    static <T extends Quacks> void quack(T ducklike) {
        ducklike.quack();
    }


    interface Quacks extends Mixin {
        default void quack() {
            System.out.println("Quack");
        }
    }

    interface Waddles extends Mixin {
        default void waddle() {
            System.out.println("Waddle");
        }
    }

    interface Mixin {
        void __noop__();
        static void create() {}
    }
}