MilanoJS 2017 - Elm in Production

Transcript

1. Elm in Production Marco Sampellegrini @_alpacaaa // @Milano_JS
2. Marco Sampellegrini Software Engineer @_alpacaaa // @Milano_JS
3. Agenda How I got to Elm What makes it unique Migrating an app to Elm @_alpacaaa // @Milano_JS
4. Why Elm? @_alpacaaa // @Milano_JS
5. Javascript in a nutshell @_alpacaaa // @Milano_JS
6. same mistakes @_alpacaaa // @Milano_JS
7. same mistakes same mistakes @_alpacaaa // @Milano_JS
8. same mistakes same mistakes u n d e f i n e d @_alpacaaa // @Milano_JS
9. same mistakes same mistakes u n d e f i n e d same mistakes @_alpacaaa // @Milano_JS
10. Insanity: doing the same thing over and over again and expecting different results. Einstein @_alpacaaa // @Milano_JS
11. @_alpacaaa // @Milano_JS
12. Functional Programming + Static typing @_alpacaaa // @Milano_JS
13. So... Haskell? @_alpacaaa // @Milano_JS
14. @_alpacaaa // @Milano_JS
15. @_alpacaaa // @Milano_JS
16. elm A delightful language for reliable webapps. @_alpacaaa // @Milano_JS
17. Started coding little games Also https://runelm.io/ @_alpacaaa // @Milano_JS
18. Real World Apps? @_alpacaaa // @Milano_JS
19. Hacker News Clone Routing Fetch data from GraphQL endpoint Non trivial UI state @_alpacaaa // @Milano_JS
20. https://elm­hn.surge.sh @_alpacaaa // @Milano_JS
21. Let's Talk about Elm! Common myths The Elm Architecture (TEA) @_alpacaaa // @Milano_JS
22. Common Myths @_alpacaaa // @Milano_JS
23. Common Myth #1 ­ FP Myth: Functional Programming == m a p ( ) . r e d u c e ( ) Truth: Functional Programming is about abstractions! @_alpacaaa // @Milano_JS
24. Common Myth #2 ­ Tests Myth: Huge and complex Test suite == Lack of errors Writing unit tests is reinventing functional programming in non­ functional languages http://noss.github.io/2009/02/25/writing­unit­tests­is­reinventing­functional­programming­in­non­functional­languages.html @_alpacaaa // @Milano_JS
25. Testing is washing the dishes. Automatic tests are a dishwasher. Types are proof that your dishes are not even dirty. https://twitter.com/runarorama/status/929754554111004672 @_alpacaaa // @Milano_JS
26. Common Myth #3 ­ Types Myth: Static Typing == Java Truth: You can write Elm code without ever writing a type signature (not a great idea though). The type system in Elm is much more powerful and expressive. @_alpacaaa // @Milano_JS
27. The static typing debate is silly. Instead the question must be, what can we prove about our programs before we run them & what is the cost? https://twitter.com/jdegoes/status/924035236035530752 @_alpacaaa // @Milano_JS
28. No Runtime Errors. Ever. @_alpacaaa // @Milano_JS
29. Breaking News Elm does not have n u l l or u n d e f i n e d @_alpacaaa // @Milano_JS
30. In case you don't know I call it my billion­dollar mistake. It was the invention of the null reference in 1965. Tony Hoare @_alpacaaa // @Milano_JS
31. Well, unless... ­ ­ Y o u c a n f o r c e E l m t o c r a s h ! ­ ­ I n c a s e y o u m i s s J S f r o m t i m e t o t i m e . . . D e b u g . c r a s h " L O L r u n t i m e e r r o r s ! " ( ) @_alpacaaa // @Milano_JS
32. The Elm Architecture @_alpacaaa // @Milano_JS
33. reactjs/redux Redux evolves the ideas of Flux, but avoids its complexity by taking cues from Elm. @_alpacaaa // @Milano_JS
34. Elm Architecture Elm Runtime Model update Html Msg view @_alpacaaa // @Milano_JS
35. All apps are written the same way. @_alpacaaa // @Milano_JS
36. Migrating an Angular app to Elm @_alpacaaa // @Milano_JS
37. @_alpacaaa // @Milano_JS
38. Rewrite one piece at a time. @_alpacaaa // @Milano_JS
39. I noticed that everyone who successfully introduces Elm at work tells the same story. They introduce Elm gradually into an existing JS project. This process works because it minimizes risk. Evan Czaplicki (Author of Elm) @_alpacaaa // @Milano_JS
40. Our Master plan Modify current app as little as possible Start serving the new Elm app at a specific route @_alpacaaa // @Milano_JS
41. In practice Elixir backend served the correct app depending on route Elm app would serve requests to / d o c u m e n t s Angular app would serve all other requests @_alpacaaa // @Milano_JS
42. Elm is ready for production use, today. @_alpacaaa // @Milano_JS
43. The Elm compiler is fantastic and super stable. @_alpacaaa // @Milano_JS
44. Ecosystem http://package.elm­lang.org/ Use p o r t s for everything that's not available as a native package. @_alpacaaa // @Milano_JS
45. Elm is great for teams. The Elm Architecture e l m ­ f o r m a t @_alpacaaa // @Milano_JS
46. Elm has fantastic error messages @_alpacaaa // @Milano_JS
47. That should be an inspiration for every error message. John Carmack https://twitter.com/id_aa_carmack/status/735197548034412546 @_alpacaaa // @Milano_JS
48. Unconventional development model Single person working on the Elm compiler, full time Not very open to contribution Elm releases take a while, focus on doing things right It's done when it's done @_alpacaaa // @Milano_JS
49. Is Elm the solution? @_alpacaaa // @Milano_JS
50. FP and Static Typing are the solution. @_alpacaaa // @Milano_JS
51. Alternatives Typescript (with f p ­ t s ) Purescript ReasonML Fable (F#) @_alpacaaa // @Milano_JS
52. Join The FP Revolution #fp on italiajs.slack.com @_alpacaaa // @Milano_JS
53. Thanks! Send me your runtime errors on Twitter: @_alpacaaa @_alpacaaa // @Milano_JS