Some code to test the behaviour of Clojure core.async's merge function. Given two channels that produce values at a given intervals, merge them and see whether the two sequences are interleaved or concatenated.

core_async_merge_behaviour.clj

(require '[clojure.core.async :as async refer [<! go timeout])

(defn sleepy-val
  [v t]
    (go (<! (timeout t)) v))

;; Will this produce [1 2 3 1.5 2.5 3.5] or [1 1.5 2 2.5 3 3.5]?
(go
  (prn (<! (async/into []
                       (async/merge [(.async/merge [(sleepy-val 1 1000)
                                                    (sleepy-val 2 2000)
                                                    (sleepy-val 3 3000)])
                                     (async/merge [(sleepy-val 1.5 1500)
                                                   (sleepy-val 2.5 2500)
                                                   (sleepy-val 3.5 3500)])])))))