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There was nothing objective about the article. The moment I saw seemingly random new lines in the rust for no reason, I knew there was going to be a “line count

by wredue 3y ago

There was nothing objective about the article. The moment I saw seemingly random new lines in the rust for no reason, I knew there was going to be a “line counts!!!!” Sentence. When there was, I stopped reading because it was apparent that all matter of objectivity is completely missing. I don’t even like rust.

reikonomusha 3y ago
It would be nice if somebody could offer what they consider to be an idiomatic Rust solution to this very routine problem in compilation if they believe the author is being intentionally deceiving. The Rust and OCaml code from the article looked decent to me. m
- deleted 3y ago
  [deleted]
- timeon 3y ago
  > The Rust and OCaml code from the article looked decent to me > RefCell<u32> I'm not sure.
  - stouset 3y ago
    For the uninitiated, this is a completely harmless choice. But it suggests a potential lack of understanding of some pretty fundamental parts of Rust.
  - foldr 3y ago
    Although I think the implementation of the gensym function is broken, the article does explain that it wasn’t possible to use &mut u32 because multiple references to the value were required. It would be more idiomatic to use Cell rather than RefCell, but there’s nothing really wrong with using RefCell as far as I can see.
- tyg13 3y ago
  I don't think anyone was claiming the author was being intentionally deceiving, just that they're not very good at writing idiomatic Rust. The first thing I'd suggest, as someone who's done their fair share of Rust compiler dev, is to stop using `Box` and `Ref` everywhere. Terms should not own their child terms; the idiomatic way to handle this is to use an arena and typed IDs, and pass a reference to the arena when you need access to the underlying data from the ID.
  - solomonb 3y ago
    So the solution to writing idiomatic code in the language whose essential feature is the ownership semantics and borrow checker is to not use the ownership semantics and borrow checker?
    - tyg13 3y ago
      This is sort of a flippant response, but I'll answer it seriously. The premise of this question is incorrect: you can't not use the borrow checker in Rust. Instead, you are satisfying the borrow checker by ensuring at the point of use (deref of the ID) that there is valid data by providing a provably-live reference to the arena in which it was allocated. In another language like C/C++, you'd just use a raw pointer, which is ergonomically-nice, but there's no guarantee that it actually points to a valid object. Rust forces you toward a solution that is guaranteed to be safe, and logically makes sense when you think about it -- nodes in a graph should not own other nodes in the graph; instead, they should be owned by the graph itself, and other nodes should simply hold references to each other. This is how you tend to implement safe and efficient graphs in C++ anyways, the only difference being that in Rust your references are indices, whereas in C++ your references are raw pointers.
      - funcDropShadow 3y ago
        But compilers deal usually with trees not general graphs.
        3y ago
itishappy 3y ago
I like Rust but this isn't one of it's strong suits. The code in the article is what Rustfmt outputs (playground link below), so it's at least syntactically idiomatic. https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=3ffdc81af7f92283f832373d7b9b967d https://play.rust-lang.org/?version=stable&mode=debug&editio...

by wredue 3y ago

reikonomusha 3y ago

It would be nice if somebody could offer what they consider to be an idiomatic Rust solution to this very routine problem in compilation if they believe the author is being intentionally deceiving. The Rust and OCaml code from the article looked decent to me. m

deleted 3y ago
[deleted]
timeon 3y ago
> The Rust and OCaml code from the article looked decent to me > RefCell<u32> I'm not sure.
- stouset 3y ago
  For the uninitiated, this is a completely harmless choice. But it suggests a potential lack of understanding of some pretty fundamental parts of Rust.
- foldr 3y ago
  Although I think the implementation of the gensym function is broken, the article does explain that it wasn’t possible to use &mut u32 because multiple references to the value were required. It would be more idiomatic to use Cell rather than RefCell, but there’s nothing really wrong with using RefCell as far as I can see.
tyg13 3y ago
I don't think anyone was claiming the author was being intentionally deceiving, just that they're not very good at writing idiomatic Rust. The first thing I'd suggest, as someone who's done their fair share of Rust compiler dev, is to stop using `Box` and `Ref` everywhere. Terms should not own their child terms; the idiomatic way to handle this is to use an arena and typed IDs, and pass a reference to the arena when you need access to the underlying data from the ID.
- solomonb 3y ago
  So the solution to writing idiomatic code in the language whose essential feature is the ownership semantics and borrow checker is to not use the ownership semantics and borrow checker?
  - tyg13 3y ago
    This is sort of a flippant response, but I'll answer it seriously. The premise of this question is incorrect: you can't not use the borrow checker in Rust. Instead, you are satisfying the borrow checker by ensuring at the point of use (deref of the ID) that there is valid data by providing a provably-live reference to the arena in which it was allocated. In another language like C/C++, you'd just use a raw pointer, which is ergonomically-nice, but there's no guarantee that it actually points to a valid object. Rust forces you toward a solution that is guaranteed to be safe, and logically makes sense when you think about it -- nodes in a graph should not own other nodes in the graph; instead, they should be owned by the graph itself, and other nodes should simply hold references to each other. This is how you tend to implement safe and efficient graphs in C++ anyways, the only difference being that in Rust your references are indices, whereas in C++ your references are raw pointers.
    - funcDropShadow 3y ago
      But compilers deal usually with trees not general graphs.
      - 3y ago

itishappy 3y ago

I like Rust but this isn't one of it's strong suits. The code in the article is what Rustfmt outputs (playground link below), so it's at least syntactically idiomatic. https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=3ffdc81af7f92283f832373d7b9b967d https://play.rust-lang.org/?version=stable&mode=debug&editio...