[shaunparker]

Rich Hickey had a great comment a long time ago on the Software Engineering Radio podcast [0] that I think speaks to this. He was asked why he didn't just make the ideas in Clojure a library for Java.

Interviewer: "Wouldn't it have been possible or simpler to add this using some kind of library or framework to an existing language? In other words, why does this kind of stuff need language support as opposed to just a library?"

Rich: "In fact it is a library. It's a library written in Java that you can use from Java. The whole thing about a language is, a language is about what does it make idiomatic and easy. So for instance, you can use the same precisely the same reference types, and the STM, and the data structures of Clojure, all from Java... The lack of idioms and language support means using exactly the same constructs, the same underlining code, from Java, is extremely painful compared to Clojure where it is the natural idiom."

I've always loved that definition of a language.

[0]: http://www.se-radio.net/2010/03/episode-158-rich-hickey-on-c...