We use Scala, and the advantages you mentioned are definitely nice, but one problem is that different Scala libraries aren't as likely to have consistent APIs as with Haskell, since pure FP is only optional in Scala but mandatory in Haskell.
This is especially frustrating when importing Java libraries. Even more so when your project uses Scala's `Future`, but the Java library uses something like RxJava and suddenly you're writing a huge wrapper library and realize you might be better off writing a Scala lib from scratch.
