core-async-sample.clj

(async/<!!
  (async/go-loop [n 0 acc {}]
    (if (< n 10)
      ;; keep aggregating values
      (recur (inc n) (assoc acc n (* n n)))
      ;; done aggregating, return the accumulated values
      acc)))

gives : {0 0, 7 49, 1 1, 4 16, 6 36, 3 9, 2 4, 9 81, 5 25, 8 64}