Like map, except f is applied in parallel. Semi-lazy in that the parallel computation stays ahead of the consumption, but doesn't realize the entire result unless required. Only useful for computationally intensive functions where the time of f dominates the coordination overhead.
; clojure/core.clj:4043 (defn pmap ([f coll] (let [n (+ 2 (.. Runtime getRuntime availableProcessors)) rets (map #(future (f %)) coll) step (fn step [[x & xs :as vs] fs] (lazy-seq (if-let [s (seq fs)] (cons (deref x) (step xs (rest s))) (map deref vs))))] (step rets (drop n rets)))) ([f coll & colls] (let [step (fn step [cs] (lazy-seq (let [ss (map seq cs)] (when (every? identity ss) (cons (map first ss) (step (map rest ss)))))))] (pmap #(apply f %) (step (cons coll colls))))))
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