[nilkn]

These questions don't seem all that unreasonable to me in and of themselves. I've barely used Scala and could answer a few of them. Several of them are prominent questions I immediately had the first time I read Scala code (e.g., the difference between classes and objects). I was able to guess at a few others from my Haskell knowledge. I have no doubt I'd encounter all the questions if I actually used Scala non-trivially.

With that said, I'm not sure if these questions are actually useful:

(1) They're pretty basic. Any good programmer could get up to speed with all these aspects of Scala in a week, possibly less. So you're not gaining anything by filtering candidates based on whether they already know this. In fact, you're wasting valuable interview time asking very low-value questions.

(2) If you really do need a Scala expert, these questions can't identify such a person.