by Kuba Waliński - We all know that JavaScript is a functional programming language. Why don't we use more functional programming concepts in our JavaScript code, then? In this talk you will learn how to start including some of them in your applications and when they might be particularly beneficial. You will also get faimilar with libraries that extend the functional capabilities of JavaScript (UnderscoreJS and FunctionalJS) and the upcoming ES6 features that make JavaScript even more functional.

1. MILAN november 28th/29th, 2014
Kuba Waliński
Fun with Functional JavaScript
kubawalinski@gmail.com
@kubawalinski
blog.kubawalinski.com
github.com/kubawalinski
ABB Łódź, Poland

2. MILAN november 28th/29th, 2014 | Kuba Waliński – Fun with Functional JavaScript
Functional Programming
• Functions as first class citizens
• can be stored in variables and data structures
• higher order functions
• can be passed as arguments to functions
• can be returned from functions
• Pure functions
• always the same result for the same params - caching
• independent from other function calls - parallelism
• no side effects - compiler optimisations
• Immutability
• Recursion
• tail call optimisation

3. MILAN november 28th/29th, 2014 | Kuba Waliński – Fun with Functional JavaScript
Functional JavaScript?!
• first class functions :)
• closures :)
• lambdas (anonymous functions) :)
• pure functions :|
• immutability :|
• tail call optimisation :(

4. MILAN november 28th/29th, 2014 | Kuba Waliński – Fun with Functional JavaScript
lodash
• very useful "utility belt" library
• port of underscore.js (comes from _)
• provides loads of functions to manipulate
• arrays
• collections
• functions
• objects
• supports curry/partial application

5. MILAN november 28th/29th, 2014 | Kuba Waliński – Fun with Functional JavaScript
functional.js
• a functional programming library for JavaScript
• created by Lee Crossley
• in constant development and use
• gaining traction
• 100+ daily npm downloads
• over 40 github stars
• currying implemented by default
• parameter order optimised for partial application

6. MILAN november 28th/29th, 2014 | Kuba Waliński – Fun with Functional JavaScript
EcmaScript 6 aka ES.next aka Harmony
• arrow functions
• tail call recursion optimisation
• destructuring arrays and objects
• spread operator
• rest parameters

7. MILAN november 28th/29th, 2014 | Kuba Waliński – Fun with Functional JavaScript
Conclusions
• Functional programming in JS is lots of fun!
• A new way to look at the language
• A welcome challenge for every programmer
• Reduces the amount of code you have to
• Write
• Read
• Reason about
• Debug
• Maintain
• Increases code readability
• Rapidly developing
• new frameworks & libraries
• new language features

8. MILAN november 28th/29th, 2014 | Kuba Waliński – Fun with Functional JavaScript
Sources
• http://dailyjs.com/2012/09/14/functional-programming/
• https://lodash.com/
• http://functionaljs.com/
• http://nullobject.github.io/fkit/
• http://eliperelman.com/fn.js/
• http://fogus.github.io/lemonad/
• https://leanpub.com/javascript-allonge
• http://www.functionaljavascript.com/
• https://github.com/kubawalinski/Talks/tree/master/Functi
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