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Comment by satvikpendem | Hacker News Reader

Note that Rust changed significantly from the side project days to 1.0 and above. It used to have features like Go-like green threads, for instance.

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I still think this is one area Rust missed the mark. Go concurrency is quite amazing. Its fast and easy to reason about. Every language can learn something by how goroutines work here. Most importantly, it feels like you're just interacting with synchronous code. There is no "what color is your function?"[0] problem.

The fundamental primitives Rust decided to adopt are just not ergonomic by comparison, and suffers from the aforementioned "What Color Is Your Function?" problem.

An otherwise great language decided to adopt an old hand grenade in regards to async primitives

[0]: https://journal.stuffwithstuff.com/2015/02/01/what-color-is-...

They are looking to fix that problem with keyword generics.

is there anywhere we can see whats being proposed there? I couldn't find anything, but I also may not know exactly where to look

https://blog.rust-lang.org/inside-rust/2022/07/27/keyword-ge...

This is an absolutely reasonable take. The thing is, this is just a divergence in values. Rust isn’t willing to accept the overheads of that style of concurrency, and is willing to trade off on the “harder to learn but with less overhead” side of this spectrum.

There's an interesting dynamic around asynchronous code in that the way to do it the fastest is to have stackless coroutines which operate on state objects on a batched fashion. This limits what you can do, but completely eliminates a lot of the overheads that are associated with async.

The inclusion of generic async semantics at the language layer is itself a compromise. Rust may have gone a little too far down the "reduce overheads" rabbit hole given that this is the case. Go definitely didn't go far enough for high-performance use cases.

All nice and dandy, but a coroutine, and doubly so a goroutine, is still a coloured function.

Remember the ~ operator?

https://github.com/rust-lang/rfcs/pull/59

And now ~ seems to be used for keyword generics.

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