ClojureScript - A functional Lisp for the browser

ClojureScript - A functional Lisp for the browser

• 1.
  ClojureScript A functional Lispfor the browser @friemens
• 3.
  Oh, what analien look!
• 4.
  Lispy syntax Ordered Associative Function Invocation var x= [1,2,3];(def x [1 2 3]) (def m {:a “Foo“}) var m = {a: “Foo“}; function bar (a) { return a + 42; } (defn bar [a] (+ a 42)) bar(0);(bar 0)
• 5.
  Interactive Development Demo https://github.com/friemen/zackzack
• 6.
  Thou shalt notmutate in place
• 7.
  Mutability causes cognitiveload var x = [1,2,3]; foo(x); After foo, what's in x?
• 8.
  ClojureScript is builton immutability (def x [1 2 3]) (foo x) (assert (= x [1 2 3]))
• 9.
  … on efficientimmutability Structural sharing x x'
• 10.
  Om on topof React
• 11.
  Databinding App state DOM event updates mutations Controller e.g. Angular transform render diff +merge DOM App state swap React+Om Shadow DOM event DOM operations are soooo sloooow.
• 12.
  Burn Hollywood Burn!* PublicEnemy (1990) *
• 13.
  Callbacks are ok,but, uhm ... function reloadAddressbook (state, event) { ask("Are you sure?", function (answer) { if (answer) { ajax.get("/addresses", function (response) { if (response.statusCode == 200) { state.addresses.items = response.body; } }); } }); } Ask for confirmation ok? Issue GET request success? Replace items But how do you implement concurrent requests?
• 14.
  CSP* with core.async= channels + go blocks Communicating Sequential Processes, Tony Hoare (1978) * (def c1 (chan)) (go-loop [xs []] (let [x (<! c1)] (println "Got" x ", xs so far:" xs) (recur (conj xs x)))) (put! c1 "foo") ;; outputs: Got bar , xs so far: [foo] a blocking read make a new channelcreates a lightweight process async write
• 15.
  core.async: no needfor callbacks Ask for confirmation ok? Issue GET request success? Replace items (defn <addressbook-reload [state event] (go (if (= :ok (<! (<ask "Are you sure?"))) (let [{s :status addresses :body} (<! (http/get "/addresses"))] (if (= 200 s) (assoc-in state [:addresses :items] addresses) state)))
• 16.
  Wrap up
• 17.
  ClojureScript is ... ...overkill for little enhancements … a mature language to tackle UI complexity … demanding to learn, but this will pay-off
• 18.
  Thank you forlistening! Questions? @friemens www.itemis.de