Javascript is awesome, and asynchronous. But some libraries are made by egocentric people : how to contain all DB interaction to the connection callback? Does the Callback soup a fatality? This talk help you to use data structure to keep safe your code. Some great ideas are comming from the functional programing world. How to use it with javascript browser and/or node.js? Is it really complicated? I write this talk because I use node.js a lot and write a lot of fix in my code to abstract database driver (couchbase, mongo, postgre...). I found an effective way to solve problems using functional programing data structure. But this talk is not for nerd or claiming functional programing superiority : some tools are cool, make your code cleanest and modular, so use it !

1. USE PROMISES,
FUTURES AND SOME
FUNCTIONAL
PROGRAMING STUFF
WITHOUT BEING A
MATH NERD.
@WAXZCE
QUENTIN ADAM AT

2. Quentin ADAM from the Clever Cloud
@waxzce on twitter – github- soundcloud – instagram ….
WHO AM I ?

3. MY DAY TO DAY WORK :
CLEVER CLOUD, MAKE YOUR
APP RUN ALL THE TIME

4. And learn a lot of things about your code, apps, and good/bad design…
KEEP YOUR APPS ONLINE. MADE WITH
NODE.JS, SCALA, JAVA, RUBY, PHP,
PYTHON, GO…

5. AND LEARN A LOT OF THINGS ABOUT
YOUR CODE, APPS, AND GOOD/BAD
DESIGN…

6. I’M NOT A MATH NERD

7. NODE.JS MAIN PROBLEM

8. SO, TRY TO KEEP IT ALIVE AND
MINIMIZE ERROR EXPOSURE

9. ON THE OTHER HAND:
THE CALLBACK SOUP

10. EXAMPLE :
DATABASE CONNECTION

11. REALLY ?
ALL DB INTERACTION IN ONE
CALLBACK ?

12. REALLY ?
UNCATCHED EXCEPTIONS BUBBLE TO
THE TOP AND KILL THE APP ?

13. REALLY ?
IF/ELSE/UNDEFINED ERROR
TREATMENT ?

14. DB DRIVER
SHOULDN’T
DRIVE YOUR
CODE
ARCHITECTURE,
THEORICALLY

15. SO, WE HAVE A PROBLEM : HOW TO USE
A VALUE WE DON’T HAVE YET, AND USE
IT IN THE FUTURE?

16. CHANGE YOUR MIND
HOW DO YOU INTERACT WITH
DATA NOW?
• Wait for it
• Possibly
blocking
i/o
Get data
from DB
and/or
WS
• Act on it
• Data
treatment
Data is
here

17. EXAMPLE

18. YOU WANT TO RETURN SOMETHING !

19. YOU MIX I/O
HANDLING WITH
YOUR BUSINESS
PROCESSES
THE OTHER PROBLEM :

20. SPLIT
Business
process and
valued
computing
I/O management
and other
“computing stuff”

21. CHANGE YOUR MIND
HOW CAN WE DO IT?
• Give all the
“recipes” about
how to deal
with this data
• You only
describe how
to manage
data you get
Get data
from DB
and/or
WS
That’s all

22. WORK ON
FUTURE DATA
YOU HAVE
PROMISED TO
YOUR CODE
;-)

23. EXAMPLE
SIMPLE PROMISE MAP

24. EXAMPLE
SIMPLE PROMISE MAP

25. MORE IMPORTANT : YOU CAN
RETURN A DATA YOU DON’T
HAVE AT THE MOMENT

26. NO MORE DEALING WITH BLOCKING I/O
IN YOUR BUSINESS CODE

27. DEALING WITH
MULTIPLE FUTURE DATA

28. And stop using boolean counter for event « ready »….
GET ALL YOU NEED TO WORK

29. REAL WORLD EXAMPLE

30. BUILT IN ERROR
MANAGEMENT

31. SIMPLE WAY : YOU CAN
RETURN SOMETING :-)

32. PROMISES
WILL MANAGE
TEMPORALITY
PROBLEMS
AND I/O IN A
SIMPLE WAY

33. NOT TOO COMPLICATED ?

34. WE’VE JUST DEALT
WITH FUNCTORS,
MONADS,
SEMIGROUPS… ALL
OF THESE
ALGEBRAIC
STRUCTURES

35. MATH WORDS, NOT SO COMPLICATED,
JUST MADE TO SHARE CONCEPTS
BETWEEN PEOPLE :-)

36. FUNCTIONAL
PROGRAMING IS NOT
A LANGUAGE : IT’S
THE ABILITY TO USE
ALGEBRAIC
STRUCTURES AND
MATH TOOLS IN YOUR
CODE
SO YOU CAN REUSE IT WHERE YOU WANT…

37. Made by the awesome Brian McKenna - @puffnfresh
FUNCTIONAL JAVASCRIPT : FANTASY
LAND SPECIFICATION AND CODE

38. https://github.com/petkaantonov/bluebird
BLUEBIRD

39. TRY IT YOU WILL

40. BUT THERE
IS MORE

41. DATA STRUCTURES CAN DRIVE
YOUR CODE TO AVOID RUNTIME
PROBLEMS

42. NULL POINTER EXCEPTION

43. PUT LOT OF IF/ELSE
IN YOUR CODE ?

44. OPTIONAL
TYPE
MAYBE YOU CAN USE

45. SAFE STORAGE BOX

46. ALGEBRA DATA MODEL
Some(DATA)
None
Option<A>

47. EXAMPLE

48. EXAMPLE

49. ACT OPTIONAL THE TIME YOU NEED,
THEN DECIDE

50. CODE IS
MORE
CLEAN &
YOU AVOID
NPE

51. Made by the awesome Brian McKenna - @puffnfresh
FUNCTIONAL JAVASCRIPT : FANTASY
LAND SPECIFICATION AND CODE

52. French article : http://www.touilleur-express.fr/2014/11/07/optional-en-java-8/
JAVA 8 OPTIONAL TYPE !

53. To understand Functional pattern value
OR TRY SCALA

54. FUNCTIONAL GOAL :
• Avoid runtime errors
• Code clarity
• Be predicable

55. LOOPS ?

57. CLASSIC ITERATION

58. CLASSIC ITERATION

59. CLASSIC ITERATION

60. MUCH MORE READABLE !

61. USING UNDERSCORE.JS
AND LODASH.JS
access to
new features
backward
compatibility
developer
hapiness

62. MODERN JAVASCRIPT
IMPLEMENTATION

63. FUNCTIONAL :
APPLY
FUNCTION ON
DATA

64. SIMPLE

65. YOU CAN USE
IT
EVERYWHERE

66. BE A BADASS !

67. I give you a www.clever-
cloud.com gift :
devoxxMA15
I’m on twitter : @waxzce
THANK YOU !
ANY QUESTIONS ?