[telios]

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.

[zem]

> it seems a bit odd to complain about this when that's what Rust is for

that's the point of the article - rust gives you a lot of low-level control, but if you don't actually need that control then you're paying the cost in ergonomics for nothing.

[bilboa]

Exactly. I did get the impression that the author is more familiar with OCaml than Rust. However I don't think they were claiming Rust's greater low-level control makes it inferior to OCaml in general. They're just saying it makes it less suitable for writing compilers, since (in the author's opinion) this level of low-level control isn't necessary for that task.