Why Async Rust?
He gives the business case:<p><i>It was clear, though usually left unsaid, that what Rust needed to succeed was industry adoption, so that it could continue to receive support once Mozilla stopped being willing to fund an experimental new language. And it was clear that the most likely path to short-term industry adoption was in network services, especially those with a performance profile that compelled them at the time to be written in C&#x2F;C++</i> ...<p><i>The other advantage of network services was that this wing of the software industry has the flexibility and appetite to rapidly adopt a new technology like Rust. The other domains were - and are! - viable long term opportunities for Rust, but they were seen as not as quick to adopt new technology (embedded), depended on a new platform that had not yet seen widespread adoption itself (WebAssembly), or were not a particularly lucrative industrial application that could lead to funding for the language (CLIs). I drove at async&#x2F;await with the diligent fervor of the assumption that Rust’s survival depended on this feature.</i><p><i>... Many of the most prominent sponsors of the Rust Foundation, especially those who pay developers, depend on async&#x2F;await to write high performance network services in Rust as one of their primary use cases that justify their funding. Using async&#x2F;await for embedded systems or kernel programming is also a growing area of interest with a bright future. Async&#x2F;await has been so successful that the most common complaint about it is that the ecosystem is too centered on it, rather than “normal” Rust.</i><p><i>I don’t know what to tell users who would rather just use threads and blocking IO. Certainly, I think there are a lot of systems for which that is a reasonable approach. And nothing in the Rust language prevents them from doing it. Their objection seems to be that the ecosystem on crates.io, especially for writing network services, is centered on using async&#x2F;await.</i> ...<p><i>None of us can control what everyone else decides to work on, and the fact of the matter is just that most people who release networking-related libraries on crates.io want to use async Rust, whether for business reasons or just out of interest. I’d like it to be easier to use those libraries in a non-async context (e.g. by bringing a pollster-like API into the standard library), but it’s hard to know what to say to people who’s gripe is that the people putting code online for free don’t have exactly the same use case as them.</i><p>Well, that says it. Rust has pivoted to web stuff. For which Go is probably better suited. Good-bye, Rust as a systems language, or for game development. Younger programmers will probably still be seeing C&#x2F;C++ buffer overflows in 2050.<p>The technical problem is that pure async, like JavaScript, is fine, and pure threading, like classic Rust, is fine. But the combination is awful.