> I guess closures in languages like Scheme can have multiple "methods"?

At the language implementation level, Scheme-like closures only have one operation, which is the ability to apply them to arguments and thus evaluate them. But as a couple of the other replies show, a closure's code can be implemented as a dispatcher which handles multiple methods. That's not a language feature, just user code.

I wrote the koan quoted above in 2003, a few years before Graydon Hoare started working on Rust. At the time, there weren't any "static" languages with built-in support for closures.

Even Python had only had read-only closure support for a couple of years at that point - so those closures couldn't be used to implement mutation of closed-over variables. (Python didn't get mutable closures until around 2008.) Java only got closure support in version 8 around 2014. C++ 11 got closures in 2011.

Of course you can implement dynamic-dispatching objects using closures in Rust or C++, but that's not going to be the equivalent of a statically-defined structure.