Functional programming for web development

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FP for WebDev advantages, approaches, problems and solutions Tuesday, April 23, 13

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About me • Alexey Kachayev • CTO at KitApps Inc. • Open source activist • Functional programming advocate • Erlang, Python, Scala, Clojure, Haskell, Go • kachayev <$> twitter • kachayev <$> gmail • kachayev <$> github Tuesday, April 23, 13

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Disclaimer #1 It’s hard to tell “is this language FP”? We will talk about: Erlang, Scala, Clojure, Haskell Tuesday, April 23, 13

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Disclaimer #2 Web is only one way to communicate. We will talk “mostly” about web. Tuesday, April 23, 13

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“Popular web” Monolit • PHP: Zend, Symphony • Python: Django • Ruby: Rails • Java: Spring, Play • ... Tuesday, April 23, 13

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“Popular web” Monolit • Easy to start • HTML-driven development • Templates-driven development Tuesday, April 23, 13

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Service- oriented • “Microframeworks” era • Python: Flask • Ruby: Sinatra • PHP: Silex Tuesday, April 23, 13

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Service- oriented Why? • Much more functionality • Much more users • Bigger development teams • Many dynamic requests from each user (ajax) • Frequent changes Tuesday, April 23, 13

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Service- oriented • High modularity • Pluggable architectures • Independent parts • Independent development • API-driven, protocol- driven Tuesday, April 23, 13

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Event-driven • Python: Twisted, Tornado, Gevent, Eventlet, Tulip • PHP: React, PhpDaemon • Ruby: EventMachine, Celluloid • JS: node.js Tuesday, April 23, 13

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Event-driven • layered architectures • 3rd party integrations • requests/response sealing • ... but async is hard • ... but “do not block” is hard • ... but error handling is hard (i.e. exceptions are hard) • ... but users still depend on each other Tuesday, April 23, 13

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And now? • Much more users (growing fast) • New ﬁelds (SaaS, PaaS, IaaS) with new problems • Sophisticated dynamic and desktop-like interfaces • Not only HTTP (WS, RTC) • Real-time communication (i.e. chats, games) • Real-time collaboration (i.e. games, trello) • Hyper-text? come on... Tuesday, April 23, 13

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What the problem is? • request-reply doesn’t work (almost at all) • concurrency is hard • fault-tolerance is hard • p2p scaling is hard • vertical scaling is hard • everything should be done yesterday Tuesday, April 23, 13

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What do we need? • easy and transparent concurrency • easy way to write async code • composability and maintainability in sophisticated systems • fault-tolerance made right • easy multi-core consuming • easy support for new protocols • etc... Tuesday, April 23, 13

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Erlang • message-passing concurrency • multi-core support • distributed systems without changes in code • “super” stable VM • “hard to broke” something • interactive development (even on running production) Tuesday, April 23, 13

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Erlang is good for... • API servers (i.e. REST, RPC) • SaaS/PaaS/IaaS cloud “without downtime” (SLAs etc) • as infrastructure (2-level OS) • streaming servers (i.e. Erlyvideo) • real-time communication (i.e. Cowboy websockets) • “super-light” client-side and shared contexts (i.e. Nitrogen) Tuesday, April 23, 13

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Hard to do with other stack(s) • SaaS/PaaS/IaaS cloud “without downtime” (SLAs etc) • as infrastructure (2-level OS), load balancers etc • streaming servers • real-time (or near real- time) communication • “super-light” client-side and shared contexts • p2p Tuesday, April 23, 13

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And more... • ChicagoBoss (rails?) • ErlyDTL (django?) Tuesday, April 23, 13

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Cases • Facebook (Chat, Chef) • Amazon (SimpleDB) • Yahoo! (Delicious) • Whatsapp (Messaging) • RabbitMQ (AMQP) • Velti (SMS gateway) • Heroku (Routing) • Github (gh-pages) • Bugsense (data analysis) • Blizzard, Wooga (games) Tuesday, April 23, 13

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Scala • JVM based, high performance • (mostly) functional paradigm • expressive type system with ATD and type inference • less code with more results • message-passing concurrency (prev. Akka) • ... XML is native Scala type Tuesday, April 23, 13

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Scala is good for... • DSLs • easy-to-read async code • API servers (i.e. with Scalatra, BlueEyes etc) • service-oriented architecture (i.e. with Finagle) • real-time communication • “super-light” client-side (i.e. with Liftweb) • if you already use Java... Tuesday, April 23, 13

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And more... • Play 2 (if you already work with Play) Tuesday, April 23, 13

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Cases • AOL • Twitter • LinkedIn • Foursquare • Meetup • Remember the Milk • Boundary • Quora • StackMob • Simple • Yammer Tuesday, April 23, 13

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Clojure • JVM based • functional paradigm, lisp- family • STM concurrency model, multi-core support • modern language, active development, fast- growing community • interactive development • macroses • JavaScript compiler (ClojureScript) Tuesday, April 23, 13

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Clojure web stack • Netty, Http-kit, Aleph, Mongrel2 • Ring • Compojure • Enlive, Laser, Hiccup • ... ClojureScript • ... Javelin, Domina • Build your own framework from parts! • Old: Noir, ClojureScript One Tuesday, April 23, 13

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Clojure is good for... • BigData • Real-time collaboration (i.e. task boards) • Concurrent documents editing • Multiplayer games • Experiments and rapid prototyping • Client-side reactive programming (sophisticated interfaces) Tuesday, April 23, 13

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Cases • Twitter (Backtype, Storm) • Factual • KamaGames • Prismatic • Groupon • Disqus • Answers.com • Simple Tuesday, April 23, 13

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Haskell, OCaml • functional languages, “ML- family” • expressive type system with ATD and type inference • high level of code modularity and composability • compact declarative syntax • green thread • math basement, compile- time program veriﬁcation Tuesday, April 23, 13

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Haskell is good for... • functional reactive programming (i.e. reactive-banana, Elm) • data parsing and types validation • compiled HTML (i.e. BlazzedHtml, Hamlet) • fun and cool stuff :) Tuesday, April 23, 13

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And more... • Happstack, Snap, Yesod, Scotty (Haskell) • ... if you already works with Haskell • ... if you want something really fast but not in C • ... if you want to make cool and fun things Tuesday, April 23, 13

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Cases • Echo (Erlang, OCaml) • Selectel (Erlang, Haskell) Tuesday, April 23, 13

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How to start? • do something simple • do something interesting • ﬁnd problem (pain?) and solve it • do not try to rewrite your project line-by-line Tuesday, April 23, 13

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Links • https://github.com/extend/cowboy • http://nitrogenproject.com/ • http://liftweb.net/ • https://github.com/twitter/ﬁnagle • http://www.scalatra.org/ • https://github.com/ring-clojure/ring • https://github.com/weavejester/ compojure • http://pedestal.io/ • http://himera.herokuapp.com/ synonym.html • http://snapframework.com/ Tuesday, April 23, 13

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IWBYP http://iwbyp.chris-granger.com/ Tuesday, April 23, 13

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Questions? * other talks: https://kachayev.github.com/talks ** me: http://twitter.com/kachayev Tuesday, April 23, 13