We don't program in a language, these days: we program in systems. I may write Clojure, with ring and schema and clj-http and clj-time and test.check and lein and jetty and many more inclusions. I may write Scala, with akka OR with scalaz and Shapeless, or a weird combination.
We never programmed in a language: we always programmed in systems. Dick Gabriel discusses the subtle paradigm shift when researchers separated the two, when the science and engineering of software parted ways in the 1990s. Before that, "language" and "system" were used interchangeably in some papers.
This is a valuable separation: now we can optimize each separately. In particular, languages are designed for extensibility, for building systems on. Both Scala and Clojure aim for this, in different ways. Let's have all the existing components on the JVM available to us, and make it clean for people to build new ones. Languages are seeds of systems, and language designers seed of communities.
Take Node.js -- it is not a new language, but it might as well be: it's a new system. The creators of Node and npm seeded a system: they left obvious necessities unimplemented, and made it easy to implement them. A community formed, and built something bigger than one small team could sustain.
When you choose a programming language, recognize that what you're choosing is a whole ecosystem and the group of people who work on it, growing and evolving that system. Do you want that to be stewarded by a strong company? or full of individual discoveries and advances, in many open source communities? to hold you to a good style or offer free combinations of multiple styles? to be welcoming to beginners, or full of serious thinkers?
[Game: Match each of these generalizations with a community: Clojure, Scala, Haskell, .NET, JVM, Ruby.]
I'm glad that people separated languages from systems, because we can build better languages and better systems from the decoupling. Both are important, and need each other. I thought about this today while my child separated her S'Mores Goldfish into marshmallow, chocolate, and graham. She used this to produce a perfectly balanced bite.
And then she ate all the marshmallows.