Terrible, terrible answer if you are mostly doing functional Scala. I've got a blog post that deals with this. Tl;dr: Java libs are good along as they are thread-safe or immutable; if they're not, you're looking at horrible side-effects where there shouldn't be any.

http://talesfromannoyance.blogspot.com/2012/05/why-im-lookin...

If you want reuse, you need to look at taking those parts and wrapping them up in SOA.

For many use cases OO Scala works just fine, functional code used where it makes sense. Our goal is to integrate with existing systems, not to seek purely functional code as a goal in and of itself.

I agree with the concept. My concern is what happens as your team grows to include others whose Scala background is more functional. There is a sense that they should be aware of the old way your code base is put together. Unfortunately things could go awry when they code new functional based code expecting functional based input.

Don't get me wrong, I like Scala. You just really have to watch its dual paradigm behavior when dealing with Java code

No, but that still doesn't excuse Scala's syntax.

We haven't had issues with Scala's syntax. Point is that Haskell isn't a viable option for most use cases.