Clojure is the most practically expressive language I've ever had the pleasure of working with. For some reason the example that immediately comes to mind is how you can use a collection as an accesser for itself, so ({:a 2 :b 3} :a) returns 2. Just a neat bit of syntactic sugar, but now if 'blacklist' is a set, you can just do (remove blacklist guests) to remove everything in blacklist from guests. There's a hundred little things like that which combine to make it a really fun and concise language to work with.