Learning Functional Programming with JavaScript

Given at JSUnconf 2016 (http://2016.jsunconf.eu/)

Transcript

1. Learning Functional Programming with JS @AnjanaVakil
2. The Recurse Center https://www.recurse.com/
3. What is functional programming?
4. What is functional programming? a programming paradigm
5. What is functional programming? a coding style
6. What is functional programming? a mindset
7. What is functional programming? a sexy, buzz-wordy trend
8. Why functional JavaScript?
9. Why functional JavaScript? object-oriented JS gets tricky (prototypes? this?!?)
10. Why functional JavaScript? safer, easier to debug/maintain
11. Why functional JavaScript? established community
12. OK, let’s do it!
13. OK, let’s do it! ...how?
14. Do everything with functions input -> output
15. Not functional: var name = “Anjana”; var greeting = “Hi, I’m ”; console.log(greeting + name); => “Hi, I’m Anjana”
16. Functional: function greet(name) { return “Hi, I’m ” + name; } greet(“Anjana”); => “Hi, I’m Anjana”
17. Avoid side effects use “pure” functions
18. Not pure: var name = “Anjana”; function greet() { console.log(“Hi, I’m ” + name); }
19. Pure: function greet(name) { return “Hi, I’m ” + name; }
20. Use higher-order functions functions can be inputs/outputs
21. function makeAdjectifier(adjective) { return function (string) { return adjective + “ ” + string; }; } var coolifier = makeAdjectifier(“cool”); coolifier(“conference”); => “cool conference”
22. Don’t iterate use map, reduce, filter
23. http://www.datasciencecentral.com/forum/topics/what-is-map-reduce
24. Avoid mutability use immutable data
25. Mutation (bad!): var rooms = [“H1”, “H2”, “H3”]; rooms[2] = “H4”; rooms; => ["H1", "H2", "H4"]
26. No mutation (good!): var rooms = [“H1”, “H2”, “H3”]; Var newRooms = rooms.map(function (rm) { if (rm == “H3”) { return “H4”; } else { return rm; } }); newRooms; => ["H1", "H2", "H4"] rooms; => ["H1", "H2", "H3"]
27. Persistent data structures for efficient immutability Mori, Immutable.js
28. Ready to try it out?
29. FP libraries for JS • Mori (http://swannodette.github.io/mori/) • Immutable.js (https://facebook.github. io/immutable-js/) • Underscore (http://underscorejs.org/) • Lodash (https://lodash.com/) • Ramda (http://ramdajs.com/) • ...and more!
30. Want to learn more?
31. “An introduction to functional programming” by Mary Rose Cook https://codewords.recurse.com/issues/one/an-introduction-to-functional-programming
32. Thanks for listening! I’m @AnjanaVakil Huge thanks to: JSUnconf organizers Diversity sponsors The Recurse Center & alums