My follow-up question would be: Is Scala still competitive to modern languages like Swift and Rust?

I experienced several drawback according to library quality and code-safety. There are too many small details that left me with an unpleasant feeling (I would take ScalaNLP/Breeze for example).

But my central issue is the VM/GC dependency. In times of GPU computing, native interface programming becomes a burden. The knowledge of object ownership improves code readability. I feel uncomfortable leaving object lifetime to a background process.