clojure - Overlapping partition in core.async -

in clojure can overlapping partitions of collection tuning step argument partition:

(partition 3 1 (range 20))  ;; ((0 1 2) (1 2 3) (2 3 4) (3 4 5) ...) 

core.async have partition function since doesn't accept step argument, can't overlapping partitions:

(let [c (chan)]   (go (doseq [n (range 20)]         (>! c n)))    (go-loop [p (async/partition 3 c)]     (when-let [v (<! p)]       (prn v)       (recur p))))  ;;[0 1 2] ;;[3 4 5] ;;[6 7 8] 

i realise having mean being able read same value channel more once. i'm aware create own function reads many values channel want , build own partitions.

however wondering if there way achieve core api provided core.async.

ps. sliding-buffer doesn't trick can't peek @ whole buffer @ once.

one way of doing create function reads channel, buffers values , puts new channel. i'm not sure how idiomatic though.

for example, function below put! vector output channel whenever required n items have been read input channel, skipping step items after every output.

(defn stepped-partition [in n step]   (let [out (chan)]     (go-loop [buffer []]       (when-let [v (<! in)]         (let [new-buffer (conj buffer v)]           (if (= (count new-buffer) n)             (do                (put! out new-buffer)               (recur (subvec new-buffer step)))             (recur new-buffer)))))    out))  (def original (chan)) (def partitioned (stepped-partition 3 2))  (go-loop []            (when-let [v (<! partitioned)]              (println v)              (recur)))  (async/onto-chan original [1 2 3 4 5 6 7 8 9])  ;=> [1 2 3] ;=> [3 4 5] ;=> [5 6 7] ;=> [7 8 9]