(defmacro defhintedfn [name args & body]
  (let [iface (gensym "HintedFn")
        hname (vary-meta name assoc :tag iface)
        vname (vary-meta name assoc
                :inline (fn [& args] `(.invoke ~hname ~@args)))]
    `(do
       (definterface ~iface
         (~(with-meta 'invoke {:tag (:tag name Object)}) ~args))
       (def ~vname nil) ; workaround for a soon-to-be-fixed bug
       (def ~vname
          (reify
            ~iface
              (invoke [this# ~@args]
                (println "specialized")
                ~@body)
            clojure.lang.IFn
              (^Object invoke [this# ~@(map #(vary-meta % dissoc :tag) args)]
                (println "generic")
                 ~@body))))))

(defhintedfn ^int hfib [^int n] (if (>= (int 1) n) (int 1) (+ (hfib (dec n)) (hfib (- n (int 2))))))

(comment
user=> (hfib 5)
specialized
specialized
specialized
specialized
specialized
specialized
specialized
specialized
specialized
specialized
specialized
specialized
specialized
specialized
specialized
)