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# mainstreamless ## Clojure 01 Никита Прокопов tonsky.livejournal.com 20 марта 2013

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# Clojure web stack Servlet Netty Mongrel2 Http-kit Aleph Ring Moustache Compojure Enlive Hiccup Laser ClojureScript Domina Enfocus Crate Javelin Reflex

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# Ring Server ←→ app contract fn [request-map] → response-map Похоже на WSGi (Python) github.com/ring-clojure/ring/blob/master/SPEC

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# Ring { :uri :query-string :request-method :headers :body ... } → { :status :headers :body }

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# Ring Нет реализации — нет зависимостей, багов, етц Маленькая — легко реализовать Низкоуровневая Вход-выход — просто тестировать Веб-сокеты не засунешь

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# Middleware (fn [handler ...] → handler’) ring.middleware: + Sessions + Cookies + Uploads + Form parsing ...

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# Диспатчинг ## Moustache (def my-app (app [“hi”] {:get “hello world only for GET!”} [“hi” name] {:get [“hello “ name]}))

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# Диспатчинг ## Compojure (defroutes app (GET “/” [] “

Hello World

”) (route/not-found “

Page not found

”))

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# Templating — цветочки ## Hiccup (html [:span {:class “foo”} “bar”]) bar (html [:div#foo.bar.baz “bang”])

bang

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# Templating — цветочки ## Hiccup (defn with-cdn [cdn-url form] (clojure.walk/postwalk (fn [node] (if (rel-asset-path? node) (cdn-url node) node) form)))

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# Templating — ягодки ## Enlive Парсинг и трансформация HTML Код отдельно от верстки Переиспользование snippets Модификации можно комбинировать Макросы!

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# Templating — ягодки ## Enlive (at a-node [:a :selector] a-transformation [:another :selector] another-transformation ...) (html/deftemplate index “tutorial/template1.html” [ctxt] [:p#message] (html/content (get ctxt :message “Nothing to see here”))

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# Templating — ягодки ## Laser Еще более функциональный (laser/document (laser/parse html) (laser/class= “meow”) (laser/content “omg”))

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# Aleph Сетевая библиотека Общение через каналы Conforms to Ring, только request и response разделены HTTP, WebSockets, TCP, UDP, Redis

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# Aleph async (defn handler [response-channel request] (enqueue response-channel {:status 200 :headers {“content-type” “text/plain”} :body “Hello World”}))

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# Aleph async (def handler (app [“sync”] {:get “response”} [“async”] {:get (wrap-aleph-handler async-handler)})) (start-http-server (wrap-ring-handler handler) {:port 8080})

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# Aleph async (def broadcast-channel (channel)) (defn chat-handler [ch handshake] (receive ch (fn [name] (siphon (map* #(str name “: “ %) ch) broadcast-channel) (siphon broadcast-channel ch)))) (start-http-server chat-handler {:port 8080 :websocket true})

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# http-kit Pure Java & Clojure, very small Server & client Ring-compliant Websockets, long-polling, streaming extensions

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# edn Data exchange format Based on Clojure syntax Rich set of elements collections, symbols, keywords Extensible for new types Self-describing (no schema) Namespaces

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# edn { :created_at #inst “1985-04-12T23:20:50.52Z” :id 209722238071619586 :id_str “209722238071619586” :retweeted false :text “tweet” :com.google.maps/geo nil :entries { :user_mentions [ { :id 1001 :indices [0 16] :name “Petrov” } ] } }

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# edn clojure.core/read-string clojure.edn/read-string (since 1.5)

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# edn clojure.core/read-string clojure.edn/read-string (since 1.5) and cljs.reader/read-string

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# ClojureScript

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# Lessons learned from Node.js Писать клиент и сервер на одном языке очень удобно! Только почему на JavaScript?

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# ClojureScript JS is broken

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# ClojureScript JS is fundamentally broken

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# ClojureScript JS is fundamentally broken Синтаксические изменения не спасут Нужно править семантику

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