Jana Dönszelmann's blog posts
Over the past two years, I've been involved with designing and implementing a new feature of rustc, called "externally implementable items". This is not a finished feature, though if you'd like you can try it on nightly already! This is the story of how externally implementable items were invented, implemented, and how some day they might be stabilized. I'm sure that is interesting to some of…
My guitar tab of "a window to the past", by John Williams
My guitar tab of "The turn of a friendly card", by the Alan Parsons Project
A feature I've always liked in languages, is the pipe operator. Some version of this can be achieved in haskell, elixir has it, and nix has a preview feature for it. And, most well known I think, bash has a pipe operator, though the way it operates on io streams is somewhat unique. Especially in interactive REPLs, like bash, the operator is super useful. So, this week I created a patch to cpython,…
While writing some machinery for dealing with spans on built-in attributes last month, I was slightly bothered by a missing method on `Iterator`. I usually work on the compiler, not the library, but I decided to write a little proposal, which was then accepted, so today it was time to try and implement it. In fairness, that implementation itself was mostly trivial, and yet right now there's no way…
The rust compiler is a giant project. Hundreds of contributors help maintain it. I consider myself quite lucky that this maintenance work has become my full time job. Most of that time though, isn't spent to work on new language features, though there is a bit of that. In fact, most maintenance is barely visible to users of the language. So what does maintaining the compiler look like?
I woke up last weekend, and someone assigned me to a PR to review. That's quite common. It fixed a crash with attributes, something I've worked a lot on. Some code crashed the compiler, but the code to reproduce it used a specific nightly feature called "contract attributes", and I didn't believe that that was the only way to reproduce the crash. So, I tried to see if any currently stable…
Deprecated is an attribute you can put on items to mark them as, well, deprecated. Any use of that item will give a warning, telling you that you're using something that's deprecated. The thing is, it doesn't always work...
Sometimes you just really need an arena. Sometimes for performance reasons, other times for lifetime-related reasons. In their most basic forms, they're just a vec with some extra guarantees. However, it's those extra guarantees that matter. I've found myself looking for the right kind of arena too many times, so here's an overview of literally everything there is. I think, let me know if I forgot…
Over the past week I've been trying to understand rust's incremental compilation model by implementing it myself. The one inside [rustc](https://rustc-dev-guide.rust-lang.org/queries/incremental-compilation.html) is already very well documented, but the implementation lives inside of a giant compiler. Maybe this is a little more accessible to you!
You might not have considered this before, but tests in Rust are rather magical. Anywhere in your project you can slap `#[test]` on a function and the compiler makes sure that they're all automatically run. This pattern, of wanting access to items that are distributed over a crate and possibly even multiple crates, is something that projects like bevy, tracing, and dioxus have all expressed…