I never said object-orientation and functional programming are opposites. (You can use objects to compute mathematical functions.) And, for that matter, imperative and functional programming aren't opposites either. (You can use imperative procedures to compute mathematical functions.) See: https://news.ycombinator.com/item?id=11180173 .

The awkwardness I'm talking about comes primarily from the non-orthogonality of Scala's features. For instance, there are situations where subclasses and implicits are both reasonable alternatives for a given programming task. On the other hand, in ML and Haskell, it is often clear which language feature is the right tool for the job.