Keywords implement many interfaces, function (IFn) being one of them. See this line in the clojure source code: public class Keyword implements IFn, Comparab

Keywords implement many interfaces, function (IFn) being one of them. See this line in the clojure source code: public class Keyword implements IFn, Comparable, Named, Serializable, IHashEq https://github.com/clojure/clojure/blob/master/src/jvm/clojure/lang/Keyword.java#L24 https://github.com/clojure/clojure/blob/master/src/jvm/cloju...