Why isn't it nearly as nice? Is there something particular about Scala such that Kafka or Akka are best implemented in it? Could you give some concrete examples (e.g. compare it with Java, C, C++, Rust, Haskell)?
(Compared to Java, C or C++ there's all the usual ML-family goodness - first-class functions, algebraic data types with pattern matching, type inference).
Scala has a for/yield construct similar to Haskell's "do notation", which is the perfect way to work with async code - it strikes the right balance of avoiding an unreadable callback pyramid of doom, but still your async yield points visible (the difference between <- and = is about as concise as it gets, but still very visible). And having HKT and allowing you to express concepts like monads means that a whole library ecosystem can build up of standard operatons operations (e.g. traverse, cataM) that work on async futures and also on other contextual/effecty types (e.g. audit logging, database transactions). That's the big advantage it has over Rust and most other competitors, and it particularly shows in things like Kafka/Akka that need to work with async a lot, but also in large programming projects generally. (What it shows up as in practice is that you can do everything in "plain old code" - all the things that need reflection/interceptors/macros/metaclasses/agents/... in other languages are just libraries in Scala - and that makes development so much easier and bugs so much rarer)
Haskell has all that - the trouble with Haskell is that "there's no way to get to there from here". I was able to go from writing Java on Friday to writing Scala on Monday - not great Scala, but working Scala, and I was just as productive as I was in Java. I couldn't've done that with Haskell.
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 When there was documentation, it would be outdated, and unmaintained.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.
I took the comment to mean that Scala is the best choice for having implemented, e.g. Kafka, and that other languages somehow aren't suited for it, and asked the question with that in mind.
