One of the kernel maintainers made social waves by bad mouthing Rust and the project to rebuild the Linux kernel in Rust. The idea of rebuilding the kernel in "Rust: the memory-safe language" not "The C in CVE stands for C/C++" makes a whole lot of sense. However, there is more to a language than how memory safe it is and whether a well known engineer calls it a "toy" language.
One of the products offered by my employer is written in Elixir, which is built on top of Erlang. Elixir had an 8 or so month period of fame, which is when the decision to write that product was made. We picked Elixir because the Erlang engine gives you a lot of concurrency and async processing for relatively easy. And it worked! That product was a beast in relatively little CPU. We had a few cases of 10x usage from customers, and it just scaled up no muss no fuss.
Where the problems with the product came wasn't in the writing, but in the maintaining and productionizing. Some of the issues we've had over the years, many of which got better as Elixir as an ecosystem matured:
- The ability to make a repeatable build, needed for CI systems
- Dependency management in modules
- Observability ecosystem support, such as OpenTelemetery SDKs
- Build tooling support usable by our CI systems
- Maturity of the module ecosystem, meaning we had to DIY certain tasks that our other main product never had to bother with. Or the modules that exist only covered 80% of the use-cases.
- Managing Erlang VM startup during deploys
My opinion is that the dismissiveness from this particular Linux Kernel Maintainer had to do with this list. The Linux kernel and module ecosystem is massive, with highly complex build processes spanning many organizations, and regression testing frameworks to match. Ecosystem maturity matters way more for CI, regression, and repeatable build problems than language maturity.
Rust has something Elixir never had: durable mindshare. Yeah, the kernel rebuild process has taken many years, and has many years to go. Durable mindshare means that engineers are sticking with it, instead of chasing the next hot new memory safe language.