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Building Functional front ends with ClojureScript @silveira_bells Isa Silveira
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Hi from Brazil
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Life as a frond-end developer since 2010 has had its ups and downs
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The ups were amazing ✨
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The JS community is really something else
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Lots of different approaches and flavors to choose from
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An infinity of boilerplates
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But the downs were painful
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Trying to make sense out of a messy soup of states and scopes
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An inception of closures to desperately deal with the messy soup of states and scopes
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Async and callback hell
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Async and callback promise hell
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Overall, JS is great, but how can I lower its cost?
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What if our front-end didn’t have to be imperative?
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Functional programming could help me with the downs big time
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Pure functions and function composition could help me dealing with state and scope
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And immutability alone could take care of 3 other huge issues
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Immutability benefits 1.Asynchronous operations 2.Performance 3.Mutation tracking
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1.Asynchronous operations 2.Performance 3.Mutation tracking Immutability benefits
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1.Asynchronous operations 2.Performance 3.Mutation tracking Immutability benefits
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Null Head Obj Obj Obj
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Head Obj Obj Obj Null Obj
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1.Asynchronous operations 2.Performance 3.Mutation tracking Immutability benefits
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“Turn and face the strange”
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Enter ClojureScript
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So what exactly is ClojureScript?
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Clojure compiled to JS
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(((( A simple guide to LISP syntax ))))
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(defn add-numbers [num1 num2] (+ num1 num2))
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(add-numbers 3 1) ;; 4
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Tooling
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A single tool for managing packages, project build, bootstrapping and scaffolding
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https://leiningen.org/
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Built-in ClojureScript REPL and live reload
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Figwheel https://github.com/bhauman/lein-figwheel
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Native immutable data structures
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core.async
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(let [channel (chan)] (go (put! channel “hello AmsterdamJS!”)) (go (.log js/console (take! channel))))
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(let [channel (chan)] (go (put! channel “hello AmsterdamJS!”)) (go (.log js/console (take! channel))))
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(let [channel (chan)] (go (put! channel “hello AmsterdamJS!”)) (go (.log js/console (take! channel))))
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Google Closure Compiler
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Closure Compilers’s superpowers 1. Dead code removal 2. Cross-module code motion
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1. Dead code removal 2. Cross-module code motion Closure Compilers’s superpowers
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1. Dead code removal 2. Cross-module code motion Closure Compilers’s superpowers
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utils.cljc
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core.cljs
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signup.cljs
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utils.cljc core.cljs signup.cljs app-state get-logged-user app-state get-field-value
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utils.cljc core.cljs signup.cljs app-state get-logged-user get-field-value
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JS interop
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vs
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Closure Compiler compliant libs also benefit from advanced compilation optimizations
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~16% smaller React’s bundle size is https://clojurescript.org/news/2017-07-12-clojurescript-is-not-an-island-integrating-node-modules
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How does it look like in practice?
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$ brew install lein
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$ lein new figwheel cljs-slides
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Back-end
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Front-end
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Shared code
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$ lein do clean, cljsbuild once min
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No matter what your problem is, remember to think of the non-obvious solutions
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“If all you have is a hammer, everything looks like a nail”
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You’re not a language, you’re not a framework, you’re not a programming paradigm
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@silveira_bells Thanks!