key_overwrite.clj

(->> {:onyx.core/batch [{:x 1}]}
     (t/apply-fn (λ [x] {:y 1}) false)
     :onyx.core/results
     (t/persistent-results!)
     (clojure.pprint/pprint))
;; =>                                                                                                                                                       
;; {:tree                                                                                                                                                   
;;  ({:root {:x 1}, :leaves ({:x 1, :message {:y 1}, :ack-val nil})}),                                                                                      
;;  :acks [],                                                                                                                                               
;;  :segments [],                                                                                                                                           
;;  :retries []}                                                                                                                                            

(->> {:onyx.core/batch [{:message 1}]}
     (t/apply-fn (λ [x] {:message 42}) false)
     :onyx.core/results
     (t/persistent-results!)
     (clojure.pprint/pprint))

;; =>                                                                                                                                                       
;; {:tree                                                                                                                                                   
;;  ({:root {:message 1},                                                                                                                                   
;;    :leaves ({:message {:message 42}, :ack-val nil})}),                                                                                                   
;;  :acks [],                                                                                                                                               
;;  :segments [],                                                                                                                                           
;;  :retries []}