Comment by grg0

My takeaway from your verbose description is:

- You don't need a visitor pattern if you have predetermined the data you are going to work with and all the operations on it (i.e., the open/closed principle does not apply.)

- For the same reason, you don't need dynamic dispatch, which is often how the visitor (and other) pattern(s) are implemented.

- The code is much simpler to understand (and debug) because it's all there in once place. It's also faster than the dynamic dispatch version because it's all known at compile-time.

- Personally: OOP is stupid, confusing, and inefficient; I think universities should only teach it as an optional course. These patterns are 50% lack of functional programming features and 50% sheer stupidity. Universities should go back to teaching real abstraction with Scheme and SICP, a MIPS-style assembly language, and stop confusing students.