There is none, without up or down casting. This is just some "guideline" that gets paraded from time to time (in OOP circles). On second thought, I am sure ther

There is none, without up or down casting. This is just some "guideline" that gets paraded from time to time (in OOP circles). On second thought, I am sure there's a "design pattern" for sum types out there. Why take the easy way out, am I right?