For me, it's Clojure's threading macros. They're like the `|>` operator on steroids. Also from Clojure, the ability to use maps and keywords as functions in a l

For me, it's Clojure's threading macros. They're like the `|>` operator on steroids. Also from Clojure, the ability to use maps and keywords as functions in a lot of cases, such as: `(map :hello [{:hello "world"}]) ; ["world"]` and `({:hello "world"} :hello) ; "world"` It comes in really handy more often than I would have thought.