Life Without Footguns (Part 1)

Transcript

1. Life Without Footguns @choonkeat March 2021
2. About • Basic • C, Perl, Java • Javascript & Ruby on Rails for 10 years • Go and Elm in the past few years • @choonkeat
3. About • Basic • C, Perl, Java • Javascript & Ruby on Rails for 10 years • Go and Elm in the past few years • @choonkeat How to do things How to NOT do things
4. Software Engineering
5. Software Engineering
6. Constant Vigilance
7. Adapters Ports Design Pattern + Best Practices Core
8. Adapters Ports Design Pattern + Best Practices Core • avoid shadowing variables • avoid cyclic dependency • avoid inheritance • avoid mutation • prefer explicit dependency • prefer stateless functions • pure functions are testable • … I can just apply functional techniques instead of switching to a functional language

9. Adapters Ports Design Pattern + Best Practices Core • avoid shadowing variables • avoid cyclic dependency • avoid inheritance • avoid mutation • prefer explicit dependency • prefer stateless functions • pure functions are testable • … I can just apply functional techniques instead of switching to a functional language

10. “Software engineering is what happens to programming when you add time and other programmers.” — Russ Cox https://research.swtch.com/vgo-eng
11. Adapters Ports Soft Social Contract Core • avoid shadowing variables • avoid cyclic dependency • avoid inheritance • avoid mutation • prefer explicit dependency • prefer stateless functions • pure functions are testable • … I can just apply functional techniques instead of switching to a functional language

12. Adapters Ports Soft Social Contract Core other people’s code urgent fi x • avoid shadowing variables • avoid cyclic dependency • avoid inheritance • avoid mutation • prefer explicit dependency • prefer stateless functions • pure functions are testable • … I can just apply functional techniques instead of switching to a functional language

13. Adapters Ports Soft Social Contract Core Compiler: LGTM 🚢 other people’s code urgent fi x
14. Life with Footguns optional static typing multi-paradigm programming language functional libraries immutable.js
15. Life without Footguns Functional architecture - The pits of success - Mark Seemann https://youtu.be/US8QG9I1XW0
16. Life without Footguns Functional architecture - The pits of success - Mark Seemann https://youtu.be/US8QG9I1XW0 How?
17. Warning: No “Freedom”
18. You Cannot Any How
19. You Cannot Any How
20. Warning: No “Freedom” Runtime Your Code
21. Runtime Warning: No “Freedom” Spend your creative energy elsewhere
22. Pure Functional Program Runtime Your Program
23. Pure Functional Program Runtime Your Program Arguments in Return values
24. Pure Functional Program Runtime Your Program Http request Render DOM Call Javascript Http response Input change Mouse move
25. I Know This! 🦖🏞 given an event, just return true or false
26. Pure Functional Program Runtime SAME callback function hooked up to ALL events Events in Return values Http request Render DOM Call Javascript Http response Input change Mouse move
27. “1 big callback”? Does It Scale? onClick = helloworld onSubmit = helloworld onLoad = helloworld what mickey mouse app can you build?
28. Does It Scale?
29. Does It Scale? Routes Http Request Handlers Callbacks
30. Does It Scale? 
 Single entry point 

31. Pure Functional Program Runtime Events in Return values Http request Render DOM Call Javascript Http response Input change Mouse move Pure Function Pure Function Pure Function Pure Function Pure Function Pure Function Pure Function Pure Function Pure Function
32. there’s a bug here but it isn’t clear 😖 if you compare to the next slide you might fi nd the problem “1 big callback” is a nightmare
33. typed values with each tag 💪 exhaustiveness check 💯 “1 big callback” is a dream
34. Ok ok “1 big callback” works…
35. But Pure Functions Only? String.toUpper List.reverse Array.map what mickey mouse app can you build?
36. Stateless Http Handler
37. Stateless Function instead of doing it…
38. Pure Function return the intention; let someone else do it
39. Pure Http Handler
40. Pure Functional Program Runtime Your Callback Function Events in Return values Http request Render DOM Call Javascript Http response Input change Mouse move
41. Runtime artist impression (not real)
42. Runtime
43. Runtime
44. Life without Footguns Functional architecture - The pits of success - Mark Seemann https://youtu.be/US8QG9I1XW0