callcc.clj

(import 'clojure.lang.ExceptionInfo)

(defn call-cc [f]
  (let [v (promise)
        e (ex-info "cc" {:v v})]
    (try (f #(do (deliver v %) (throw e)))
         (catch ExceptionInfo ex
           (if (identical? ex e)
             @(:v (ex-data ex))
             (throw ex))))))

(defn search [pred coll]
  (call-cc
   (fn [return]
     (doseq [el coll]
       (if (pred el)
         (return el))))))

(search even? [1 2 3]) ;=> 2