I was actually thinking something simpler; just having all your types implement an interface, and then following the general "tell, don't ask" dictum. Handlers

I was actually thinking something simpler; just having all your types implement an interface, and then following the general "tell, don't ask" dictum. Handlers are useful for some more complex use cases, as is the visitor pattern, but they're frankly overused. It's often enough to create an interface and let the classes handle their own class-specific logic. And polymorphism is not just a sugared version of pattern matching. Each gives you a different kind of flexibility. Polymorphism makes it easy to add new types to an existing set of operations, and pattern matching makes it easier to add new operations to an existing set of types. Which one you need depends on your use case. The common knowledge can get a bit tricky here, though. For example, functional programming is often touted as being ideal for programming language experimentation, because you have pattern matching, but I have found that OOP is more to my taste in this area. The reason is because, nowadays, the set of basic operations a compiler or interpreter needs to do is fairly well-established and static. But the list of things you need to operate on - that is, the set of features in the language you're implementing - will change as you add or remove features from the language.