Reagent input not updating
I turned out to be pretty easy - the "component" function can return not a template, but a function returning template. This way the outer function will be executed only once (and we can put let there), and inner will be executed on every re-render:
(defn new-user [] (let [v (atom "")] ; The returned function will be called on every re-render. (fn [] [:div [:input {:type "text" :value @v :on-change (fn [evt] (reset! v (-> evt .-target .-value)))}]])))