client.cljs

(defmulti control (fn [action] action))

(defmethod control :init [_ [init-state] _]
  init-state)


(defonce reconciler
  (scrum/reconciler {:state (atom {}) ;; <= client-side state
                     :controllers {:user control}})) ;; <= action handlers


(defn render [state] ;; <= initial state rendered into HTML on server
  ;; ... dispatch state to controllers ...
  (rum/mount (App reconciler)
             (. js/document (getElementById "app"))))

server.clj

(defn make-resolver [db]
  {[:user] #(find-user db)}) ;; <= data resolver for subscription [:user]

(def reconciler (-> db make-resolver scrum/reconciler))

(def html (-> reconciler App rum/render-html))

(def state @(:state reconciler)) ;; <= retrieve resolved data after rendering

(render-page html state) ;; <= render HTML document

ui.cljc

;; UI component with subscription [:user]
(rum/defc App < rum/reactive [r]
  (let [user (rum/react (scrum/subscription r [:user]))]
    [:div
     [:div (:name user)]
     [:div (:email user)]]))