(ns lab32)

(def futureCap 3)

(defn pfilter [pred coll]
  (let [n 4
        chunked (fn chunked [c]
                  (lazy-seq
                    (if (not-empty c)
                      (cons (take futureCap c) (chunked (drop futureCap c))))))
        fut (fn [c] (map #(future (do (println "fut" %) (doall (filter pred %)))) c))
        step (fn step [[x & xs :as vs] r]
               (lazy-seq
                 (if-let [s (seq r)]
                   (cons (deref x) (step xs (rest s)))
                   (map deref vs)
                   )))
        fc (fut (chunked coll))]
    (flatten (step fc (drop n fc)))
    )
  )


(let [coll `(6 4 5 2 3 2 8 0 3 7 9 11)
      pred (fn [x] (do
                     (println (format "lazy%d " x))
                     (Thread/sleep 5000)
                     (even? x)
                     ))
      ]
  (do
    (time (doall (pfilter pred coll)))
    (time (doall (filter pred coll)))
    )
  )

(shutdown-agents)