gistfile1.clj

;; Dispatch message to object
(defmacro call* [obj, getter & args]
  `(let [object# ~obj]
    (((keyword '~getter) @(type object#)) object# ~@args)))

(defrecord Dodo [instance])

(def DodoClass (new Dodo nil))


(defrecord SimpleList [values])

(def SimpleListClass
   (merge DodoClass
      {
      :instance (with-meta (new SimpleList [1 2 3 4]) {:type (var SimpleListClass)})
      
      :values (fn [self] (-> self :values))
      }))

(println (call* (-> SimpleListClass :instance) values))


(def ExtendedClass
   (merge SimpleListClass
      {
      :instance (with-meta (new SimpleList [4 5 6]) {:type (var ExtendedClass)})

      :shift (fn [self]
         (with-meta self
            {:type (ref
               (merge @(type self)
                  {
                  :values (fn [self] (subvec (-> self :values) 1))
                  }))
            }))
      }))

(def x (call* (-> ExtendedClass :instance) shift))
(println (call* x values))