We switched from Scala 2 to Rust

Scala 3 (programming language similar to scala 2) is failed project. Some often used scala 2 libraries can't be ported to scala 3 due to removed features (macros are much less capable, compiler plugins, DSL), lot of people writing scala libs left ecosystem, death of Akka (went commercial with really high pricing). Big companies supporting Scala for big data (Facebook, Twitter, LinkedIn) declared years ago that they will not support scala 3 and drop language for new projects.

Problem with Java is that after Oracle started to charge for commercial use - Java usage in new projects dropped by 30% over following 3 years. People started leave Java ecosystem if they can. Java 17 is free for production again, but you can't redistribute it. Common strategy is to bundle java runtime with app. damage is already done. Why develop in JDK 17 if next version can be paid again? And in year 2023 new pricing: Java support program is now 5X more expensive.

We moved to rust because it can be easily embedded into C/C++ apps, webasm target, memory safe design. There is not much alternatives: Python, nodejs, Go, C# - that's pretty much it. PHP is pretty dead. python sucks a lot, Go is too limited, nodejs is okay - lot of good tools but 2X slower than java without wasm.