I don't quite follow the algorithm here, but I'm not sure the `gensym` Rust implementation works as expected. `RefCell::clone` does not return a copy of the reference; it returns a new `RefCell` with the current `RefCell`'s value, resulting in duplicate IDs. However, a `RefCell` isn't even necessary here, since a `Cell` would do just fine - and you'd pass around a reference to that `Cell` instead of cloning it.
It does feel like the code was ported as-is to Rust, and only adjusted slightly to compile; there are going to be pain points as a result of this process. I suspect this is the source of some of the author's complaints, especially given:
> Although it provides us with a greater sense of how the code is executing, it brings very little value to the algorithm itself.
Rust is, in general, for people who find value in having that information; it is okay to not want to have to worry about ownership, borrowing, safety, etc., but it seems a bit odd to complain about this when that's what Rust is for? If you want to focus on just the algorithm, and not how it's executing, then OCaml is definitely a valid choice.
However, the point about GADTs - can Rust's recently-stabilized GATs not work in the same way? Though I will admit that Rust's GATs don't seem nearly as powerful as OCaml's GADTs in this regard.
It does feel like the code was ported as-is to Rust, and only adjusted slightly to compile; there are going to be pain points as a result of this process. I suspect this is the source of some of the author's complaints, especially given:
> Although it provides us with a greater sense of how the code is executing, it brings very little value to the algorithm itself.
Rust is, in general, for people who find value in having that information; it is okay to not want to have to worry about ownership, borrowing, safety, etc., but it seems a bit odd to complain about this when that's what Rust is for? If you want to focus on just the algorithm, and not how it's executing, then OCaml is definitely a valid choice.
However, the point about GADTs - can Rust's recently-stabilized GATs not work in the same way? Though I will admit that Rust's GATs don't seem nearly as powerful as OCaml's GADTs in this regard.