Clojure Protocols #clojure

gistfile1.clj

(defprotocol Foo
  "Does Foolike things"
  (bar [a b] "does stuff with a & b")
  (baz [a] "does stuff with a"))

(extend-protocol Foo
  nil
  (bar [_ _] nil)
  (baz [_] nil)

  String
  (bar [a b] {:a a :b b}))

When you extend a protocol to a given type you only need to implement the methods that make sense for you. You'll get exceptions if you try calling a function you haven't implemented. Sweet :)