It might not qualify as "really hard thing involving heavy concurrency and lots of state", but I'm nearly done writing a service that interacts with http://tile

It might not qualify as "really hard thing involving heavy concurrency and lots of state", but I'm nearly done writing a service that interacts with http://tile38.com http://tile38.com. I initially wrote it in Kotlin, and 2 weeks ago I ported it to Rust. I'm still learning the language, so I haven't touched the "fearless concurrency" stuff, but so far it's looking very good. ~30% CPU time, 1-5% RAM use at peak; compared to the JVM. I plan on writing about it, and open-sourcing the code (both Kotlin and Rust repos). Chasing a hectic work deadline at the moment.