i.e. what do I not understand about map and/or promises.
(import '(java.util.concurrent Executors))
(def pool (Executors/newFixedThreadPool 10))
(defn sleep-for [t] (. Thread (sleep t)) t)
(defn fastest-first-map [f coll]
(let [ps (map (fn [_] (promise)) (range (count coll)))
a (agent ps)
delivery-fn (fn [result]
(send a (fn [[p & ps] result*]
(deliver p result*)
ps)
result))]
(dorun (map (fn [v]
(.submit pool #(delivery-fn (f v))))
coll))
ps))
(defn do-it [] (fastest-first-map (fn [f] (f))
(map partial (repeat sleep-for)
(shuffle (range 100 1000 100)))))
;; This works as expected
(time @(first (do-it)))
;;"Elapsed time: 100.986 msecs"
;; => 100
;; This doesn't return until the entire result is dereferenced
(time (first (map deref (do-it))))
;;"Elapsed time: 900.525 msecs"
;; => 100
(chunked-seq? (do-it))
;; => false
I'm at a loss on this one.
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