The document discusses the use of monads in managing complexity in programming, emphasizing their role in handling side effects and improving code reuse. It covers concepts such as functors, monoids, and the application of monads through examples and business rules implementation. The author concludes that monads can lead to more declarative and reusable code while effectively managing potential complexity.

1. Monads in Practice
Christophe Marchal | Software Architect

2. A couple of links
christophe.marchal@ilegra.com
@toff63
http://github.com/toff63
http://francesbagual.net

3. Disclaimer

4. Manage complexity with Monad

5. Study Monads online is hard

6. Academic talks
Functor
Monoids
Monads
Category
theory

7. Category Theory

8. Function
Monoids
Associative
( 1 + 2 ) + 3 = 1 + ( 2 + 3 )
InitiAl Value
Result stay in the same
category

9. Monoid Example

10. Monoid

11. Functor
Things that can be map over
capacity BEHaviour
map

12. Functor: Example

13. Functor: Example

14. Monads

15. Problem it solves

16. Scenario
F 1 F 2

17. sweet
Monads Rules: function to create it

18. Broken Composition
F 1
F 2 sweet

19. Monads Rules: You need a Functor
F 1
map ( f 2 )
sweet

20. Scenario
F 1 F 3
sweet

21. Problem: Nested Monad
F 1
sweet
map ( f 3 )
sweet

22. F 1
sweet
Flatmap ( f 3 )
Monads Rules: You need a Flatmap

24. Business rule
TRUE False
age > 18
Authorized Not
Authorized

25. Business rule implementation

26. What we want

27. Monad (?) Code

28. Trade-off
More code than before
Better API
Easy to reuse
Potential complexity Managed

29. Traditional Code

30. Side Effect
Our method can return either a sequence
either null

31. Exist
?
TRUE False
null ?
Riendutout quelquechose

32. Encapsulating if null with Option

33. Creating our OptionBagual

34. Code with Options

35. Business code

36. Side Effect
Our method can return either an option
[sequence] either throw an exception

37. Try!
Success Failure
Try to
execute
Gremio Inter

38. Encapsulating try/catch with Try

39. Encapsulating try/catch with Try

40. Code with Try

41. Business code

42. Connection Handling

43. No silver bullet

44. Loan Pattern

45. Final Code

46. Conclusion
● NO IFs
● Border cases handled on demand
● More declarative types
● Highlight business code
● Easy to create
● More reusable code

47. Thank You!
Christophe Marchal | Software Architect