using System;

using static ColliderLibrary;

​

SpaceObject x = new Asteroid(101);

SpaceObject y = new Spaceship(100);

​

Console.WriteLine(Collide(x, y));

​

​

string Collide(SpaceObject x, SpaceObject y) =>

    x.Size > 100 && y.Size > 100

        ? "Big boom!"

        : CollideWith(x as dynamic, y as dynamic); // Dynamic dispatch to CollideWith method

​

class ColliderLibrary {

    public static string CollideWith(Asteroid x, Asteroid y) => "a/a";

    public static string CollideWith(Asteroid x, Spaceship y) => "a/s";

    public static string CollideWith(Spaceship x, Asteroid y) => "s/a";

    public static string CollideWith(Spaceship x, Spaceship y) => "s/s";

}

​

record SpaceObject(int size) {

    public int Size = size;

}

​

record Asteroid(int size) : SpaceObject(size);

record Spaceship(int size) : SpaceObject(size);