You can have multiple `f` with different "arguments" (if you consider a receiver a part of arguments) without the full multimethod, which is actually pretty har

You can have multiple `f` with different "arguments" (if you consider a receiver a part of arguments) without the full multimethod, which is actually pretty hard to get it right and only one language out of your examples (Julia) does that. Other two languages (Rust and Go) fully retain classes, slightly obscured to fit with traits and interfaces respectively.