new_syntax.clj

(defprotocol Foo
  (is-foo [this, a :- Number] :- Number)
  (is-bar [this, a :- Int] :- Int
          [this, b :- Number] :- Number)
  (is-baz [this, a :- Int] :- Int
          [this, a :- Int, b :- Int] :- Int
          [this, a :- Int, b :- Int, c :- Int] :- Int))

old_syntax.clj

(ann-protocol Foo
              is-foo
              [Foo Number -> Number]

              is-bar
              (Fn [Foo Int -> Int]
                  [Foo Number -> Number])

              is-baz
              (Fn [Foo Int -> Int]
                  [Foo Int Int -> Int]
                  [Foo Int Int Int -> Int]))
(defprotocol> Foo
  (is-foo [this a])
  (is-bar [this a])
  (is-baz [this a]
          [this a b]
          [this a b c]))