Clojure - prioritized rich immutable data. I haven't found any other language that prioritizes open data sets: where a map has "a" and "b" but it could also have "c" and "d", if you only care about "a" and "b" it doesn't matter if the other data just tags along.

And I say "rich" data since other languages are pretty data-centric (scheme of course), but not any that prioritize immutable hash maps, sets, vectors, linked-lists, etc.