One page of async Rust
2026-02-17 19:42https://dotat.at/@/2026-02-16-async.html
I'm writing a simulation, or rather, I'm procrastinating, and this blog post is the result of me going off on a side-track from the main quest.
The simulation involves a bunch of tasks that go through a series of
steps with delays in between, and each step can affect some shared
state. I want it to run in fake virtual time so that the delays are
just administrative updates to variables without any real
sleep()ing, and I want to ensure that the mutations happen in the
right order.
I thought about doing this by representing each task as an enum
State with a big match state to handle each step. But then I
thought, isn't async supposed to be able to write the enum State and
match state for me? And then I wondered how much the simulation
would be overwhelmed by boilerplate if I wrote it using async.
Rather than digging around for a crate that solves my problem, I thought I would use this as an opportunity to learn a little about lower-level async Rust.
Turns out, if I strip away as much as possible, the boilerplate can fit on one side of a sheet of paper if it is printed at a normal font size. Not too bad!
But I have questions...
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