> Too bad there's not really a ML/AI ecosystem around (besides Spark, which seems to be losing favor partially because of its embarrassing performance), because using Python is such a drag.

I think it's not that bad. Sure, it loses to Python, but that's some tough competition.

Personally, I find that smile[1] covers most use cases. Breeze[2] also has a lot of love, but I'm not much of a fan of the `UFunc` abstraction.

I'm also really excited about polynote[3]. It's still a bit green and only supports Scala 2.11/2.12, but it's such a joy to be able to use Scala in notebooks :). You also get Python interop, in case you need to use some specific python library.

P.S.: I hope that Scala's ML/AI libraries other than Spark keep growing, because "embarassing" is a nice way to describe it's performance on everything that's not a "really-huge dataset".

1: https://github.com/haifengl/smile 2: https://github.com/scalanlp/breeze 3: https://github.com/polynote/polynote