scratch.clj

(require '[clojure.core.async.impl.protocols :as impl]
         '[clojure.core.async.impl.dispatch :as dispatch])

;;=> nil

(extend-type java.util.concurrent.CompletionStage
  impl/ReadPort
  (take! [this handler]
    (.whenCompleteAsync this
                        (reify
                          java.util.function.BiConsumer
                          (accept [_ result exception]
                            (.lock handler)
                            (let [good (and (impl/active? handler)
                                             (impl/commit handler))]
                              (.unlock handler)
                              (when good
                                (dispatch/run #(good (or exception result))))))))
    nil))

;;=> nil

(require '[clojure.core.async :as async])

;;=> nil

(def cf1 (java.util.concurrent.CompletableFuture.))

;;=> #'user/cf1

(first (async/alts!! [(async/timeout 1000) cf1]))

;;=> nil

(.complete cf1 "Foo")

;;=> true

(first (async/alts!! [(async/timeout 1000) cf1]))

;;=> "Foo"