1. USE PROMISES,
FUTURES AND SOME
FUNCTIONAL
PROGRAMING STUFF
WITHOUT BEING A
MATH NERD.
@WAXZCE
TAKEOFF CONFERENCE

2. WHO AM I ?
CEO at www.clever-cloud.com
Polyglot developer
@waxzce on twitter

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

4. I’M NOT A MATH NERD

5. NODE.JS MAIN PROBLEM

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

7. ON THE OTHER HAND:
THE CALLBACK SOUP

8. EXAMPLE :
DATABASE CONNECTION

9. REALLY ?
ALL DB INTERACTION IN ONE
CALLBACK ?

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

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

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

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

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

15. EXAMPLE

16. YOU WANT TO RETURN SOMETHING !

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

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

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

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

21. EXAMPLE
SIMPLE PROMISE MAP

22. EXAMPLE
SIMPLE PROMISE MAP

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

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

25. DEALING WITH
MULTIPLE FUTURE DATA

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

27. REAL WORLD EXAMPLE

28. BUILT IN ERROR
MANAGEMENT

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

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

31. NOT TOO COMPLICATED ?

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

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

34. 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…

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

36. DEMO MADE WITH PACTA
IMPLEMENTATION
Node.js + browser implementation, totally agnostic javascript,
Fantasy Land compatible + Promises/A+ compatible
made by Paul Mucur with help from Rodolphe Belouin

37. TRY IT YOU WILL

38. BE A BADASS !

39. THANK YOU !
ANY QUESTIONS ?
I’m on twitter : @waxzce
I give you a www.clevercloud.com gift :
takeoff2014