State transformers and watchers.
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(ns your-app
(use [pasta.core :only [watch-transition]])
(use-macros [pasta.macros :only [deftransition]]))
;; Create an atom of a map to hold the entire state of the app.
;; Put everything you need to reconstruct the view.
(def app (atom {:page 1
:loading :false}))
;;;;; PURE ;;;;;
;; Deftransition defines a function that takes the current state and arbitrary
;; number of arguments and returns a diff map to the state.
;; No side-effectful operation should happen in a transition.
(deftransition stop-load [_state]
{:loading false})
(deftransition next-page [{:keys [page]}]
{:page (inc page)
:loading true})
(deftransition prev-page [{:keys [page]}]
{:page (dec page)
:loading true})
(deftransition page-to [_state page-n]
{:page page-n
:loading true})
;;;;; IMPURE ;;;;;
;; Watch-transion registers a side-effectful function that will get invoked
;; whenever the specified field of the state changes.
;; Do not mess with the state in a watcher.
(watch-transition app :load
(fn [{:keys [loading]} _old-state]
(if loading
(.show (js/jQuery ".loading-indicator"))
(.hide (js/jQuery ".loading-indicator")))))
(watch-transition app :page
(fn [st]
;; retrieve html, replace the content, etc.
(stop-load app)))
(.on js/document "click" (js/jQuery ".next-btn")
#(next-page app))
(.on js/document "click" (js/jQuery ".prev-btn")
#(prev-page app))
(.on js/document "click" (js/jQuery ".pager")
#(page-to app (.getAttribute (.-target %) "data-page")))
;;....Copyright © 2013 Minori Yamashita ympbyc@gmail.com
Distributed under the Eclipse Public License, the same as Clojure.