I think the parent comment was talking more about using those libraries with Scala, not necessarily implementing them. Can't speak too much about the others, b

I think the parent comment was talking more about using those libraries with Scala, not necessarily implementing them. Can't speak too much about the others, but I recently looked into using Akka with Java. Akka itself had a good deal of documentation for Java users. However, other related products (look tools for monitoring Akka, etc) were clearly treating Java as a second class citizen. When there was documentation, it would be outdated, and unmaintained. I ran into this over and over again, which weighted heavily on my decision to not use Akka. I'm not quite sure if there is anything about the language that would have made it particularly challenging (doubt it), but it definitely seems like the community built around it is more Scala centric. And that in itself makes it challenging to use with anything else.