Second, what polyglot programming really offers? It’s worth to see 50 lines of Java code can be reduced 10 lines of Clojure code but for what. At least at the backend most of the code do nothing more than run few or more SQL queries, transform result to XML or JSON. Do we really need different programming languages for that? I doubt and you should too. Most of the programming tasks can be accomplished in single language without loosing any comfort and productivity because of existing frameworks, tools or libraries. I don’t think we should use one language for everything, but using different languages even sexy languages for very similar use cases is waste of time and resource.