Presentation at Nerdear.la 2017

1. OOP is not Dead
or why we should stop seeing FP as its opponent or as silver bullet
Hernán A. Wilkinson
@hernanwilkinson
agile software development & services

2. This will not be a war!

3. A little bit of
Context…

6. A little bit of
History…

7. Structured Programming,
when?

11. Object Oriented
Programming, when?

12. Simula 67
Ole-Johan Dahl y Kristen Nygaard

13. Simula 67
Ole-Johan Dahl y Kristen Nygaard

14. OOP before
Structured
Programming??

21. Functional Programming,
when?

22. John McCarthy

26. What does make Lisp great?
(always great! not, “great again”  )
LISP

27. (define (filtrar lista condicion)
(cond
((esta-vacia? lista) lista-vacia)
((condicion (primero-de lista)) (concatenar (primero-de lista) (filtrar (resto-de lista) condicion)))
(else (filtrar (resto-de lista) condicion))))
(filtrar ‘(1 4) (lambda (x) (< x 3)))
—> ‘(1)
(define smaller-than-three (lambda (x) (< x 3)))
(filtrar ‘(1 4) smaller-than-three)
—> ‘(1)
(define (smaller-than n) (lambda (x) (< x n)))
(filtrar ‘(1 4) (smaller-than 3))
—> ‘(1)
Lambda Functions

28. Meta-Circular

29. Meta-Circular

30. Meta-Circular

31. Meta-Circular

32. Meta-Circular

33. Dynamic! - REPL

34. What is Object Oriented
Programming?

35. Alan Kay

36. Dynabook (1970)

38. I invented the term
Object-Oriented and I
can tell you I did not
have C++ in mind.
Java and C++ make you
think that the new ideas are
like the old ones. Java is the
most distressing thing to hit
computing since MS-DOS

39. What is Object Oriented?
• MUST
• Everything is an Object (data is an object, code is an object, classes are
objects, everything is an object!)
• Computation is done sending messages
• EITHER OR BOTH
• Classes and Sub classification as means of knowledge organization
• Objects as prototypes as means of knowledge organization
• REALLY NICE TO HAVE
• Immediate feedback
• Completely Reflective Environment (Meta-Circular)

40. Dynamic! More than REPL, Inspectors!

41. What OO is not
• Data types - int, long, double, etc. They are not objects
• Statements - for, while, if, etc. They are not messages
• Static methods - There is no “self/this” on static methods
• Final/Seal methods – There is no message send when used
• When ”code” is not an Object – No Closure or no Lambda, i.e. Java previous
1.8
• JEE is no OO, it is structured programming in Java
• Anemic classes is not OO (Services with DTO, etc)
• Use of Inheritance for Code reuse is not good OO (i.e. ActiveRecord , white
box frameworks, etc)
• Dependency Injection abuse is not OO
• IoC abuse is not OO

42. This is not OO – Filter in Java

43. What is Functional
Programming?

44. Wikipedia’s definition
• […] treats computation as the evaluation of mathematical functions
and avoids changing-state and mutable data.
• It is a declarative programming paradigm, which means programming
is done with expressions[…]instead of statements.
• Missing concepts from Wikipedia:
• Lambda functions (which allow High Order functions)
• Runtime support for recursive implementations (aka: tail recursion
elimination)
• Arguable:
• Lazy evaluation (more or less)
• Macro

45. Good OO Design favors
Immutable Objects!

46. This is not OO!

47. This IS OO!

48. Real OO Languages represent
“Code” as an object
(Closure  High Order Functions)
• Smalltalk since the ‘70s
• ”Closures got famous because Java don’t have them” (Anonymous)

50. Some conclusions - Good OO implies:
• Immutable objects when representing immutable
entities
• Closure  “High order functions”
• Message sending all the way (expressions)
• Consistency (everything is an object)
• Knowledge representation and classification
(Programs are Models!)

51. Some conclusions about FP
• It is a mistake to think that FP is going to solve all the
software design problems.
• Design are made by humans, not by programming languages
(even though they influence design decisions)
• FP will suffer from the same “miss-used” problems as OO
suffers now
• FP does not provide a way to organize the knowledge
represented in the software  data structures are not
enough, we know that from Structured Programming

52. Some conclusions
•OOP vs. FP is an absurd dichotomy
•OOP and FP complement each other
•Do not act as a “Pop Programmer”

53. From where “language
programming paradigms shifts”
will come from?

54. For sure NOT from
• Performance improvements
• Less verbose languages
• Better type system (other complete topic to discuss)
• It is “normal science” (khun-onian way to say “more of
the same”)

55. They will come from
• Better tools to help human-machine communication
•Better environments to “augment” human intellect
•More dynamic environments to improve immediate
feedback
•…
•Let’s see some examples

59. For a new
definition of
Programming
Paradigm!
For better tools!

60. agile software development & services
¡Gracias!