react.cljs

(defn component [ref render-fn & {:keys [on-mount on-unmount]}]
  (let [comp (React/createClass (clj->js
              { :render               (fn [] (crate/html (render-fn @ref)))
                :componentDidMount    (or on-mount identity)
                :componentWillUnmount (or on-unmount identity) }))]
    (add-watch ref :react 
      (fn [_ _ old new]
        (when (not= old new) (.forceUpdate comp))))
    comp))

(def state (atom {:title "Vasya"}))

(component state (fn [val]
  [:div.class (str "Hello" (:title val))]))

(swap! state assoc :title "Petya")

Я только что подумал, что может лучше будет так:

(defn component [ref render-fn]
   (let [comp (React/createClass (clj->js {:render (fn [] (tmpl (this-as this (render-fn (.-props this))))}))]
      (add-watch ...)
      comp))

(let [state (atom {:count 0})]
   (component state (fn [props]
       [:div.class {:on-click #(swap! state update-in [:count] inc)} (:count @state)]))

Не очень хорошо, что state надо и создавать, и передавать, но зато он спрятан, и это может макро исправить.