Spark's written in Scala, so Scala will presumably always be the best-supported language. On the inside Spark's also pretty intimately tied to some Java impleme

Spark's written in Scala, so Scala will presumably always be the best-supported language. On the inside Spark's also pretty intimately tied to some Java implementation details (e.g., it uses Java serialization to push code around), so any non-JVM language is always going to have to deal with a bit of friction. That said, from my experience the Python integration is still first-class. I think it might lag the Scala APIs a bit, but that isn't a huge deal unless you really need to be on the bleeding edge at all times. The only really big downside in my book is that there's a small performance hit you take by choosing to use the Python API instead of the Scala one, and that might compound into something of practical significance if you're using it for really big data tasks. I assume you'd have similar problems using it with R or a .NET language.