Clojure protocols, types, and records

gistfile1.clj

; Here is our protocol
(defprotocol ThirdGradeMath
  (add [this])
  (sub [this])
  (mul [this])
  (div [this]))

;And our record
(defrecord MathRecord [x y]
  ;Let's implement our protocol
  ThirdGradeMath
  ;Implementing only one function
  (sub [this]
    (- x y)))

;Let's use make a record and get the value of y
(:y (MathRecord. 2 5))
;5

;Let's call sub on a record
(.sub (MathRecord. 1 1))
;0

;And our type
(deftype MathType [x y]
  ;Let's implement our protocol
  ThirdGradeMath
  ;Implementing two functions
  (add [this]
    (+ x y))
  (mul [this]
    (* x y)))

;Let's get the value of x
(.x (MathType. 1 2))
;2

;Let's call mul
(.mul (MathType. 2 2))
;4