gistfile1.clj

; before
(fn [{:keys [memory registers] :as system}]
    (let [value  (memory/load memory
                              (registers :pc))]
         (-> system
             (->/in [:registers]
                    (assoc r value)
                    (update-in [:pc] inc)))))])

; after
(m/do value <- read-next-byte
      (set-register r value))])