Dysfunctional Programming (phpnw13)

Transcript

1. Dysfunctional
   Programming
   

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2. @igorwesome
   

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6. Immuteability: The property of functional
   programmers that prevents them from shutting up
   about pure functional programming.
   – Reg Braithwaite
   @raganwald
   

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7. dys·func·tion·al
   

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8. php λ
   

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9. Paradigms
   

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10. procedural
    Object-
    Oriented
    functional logic
    

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11. Imperative
    Declarative
    

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12. Structure
    Time & State
    

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13. Structure
    

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15. ‘sup?
    

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17. it’s not about the money
    

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18. • Message passing
    • Interfaces
    • Composition
    • (Not inheritance)
    

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19. Actor model:
    Asynchronous
    

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22. f g h
    

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23. tools and materials
    

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24. • Value semantics
    • Higher-order functions
    • Lazy evaluation
    

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25. The Garbage
    Overfloweth
    

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26. $numberCollection = new NumberCollection();
    $numberParser = new SimpleNumberStringParser();
    $firstParsedNumber = $numberParser->parse('1');
    $firstNumber = new SimpleNumber($firstParsedNumber);
    $firstNumberProxy = new CollectionItemNumberProxy($firstNumber);
    $numberCollection->add($firstNumberProxy);
    $secondParsedNumber = $numberParser->parse('1');
    $secondNumber = new SimpleNumber($secondParsedNumber);
    $secondNumberProxy = new CollectionItemNumberProxy($secondNumber);
    $numberCollection->add($secondNumberProxy);
    $addition = new AdditionOperator('SimplePHPEasyPlus\Number\SimpleNumber');
    $operation = new ArithmeticOperation($addition);
    $engine = new Engine($operation);
    $calcul = new Calcul($engine, $numberCollection);
    $runner = new CalculRunner();
    $runner->run($calcul);
    $result = $calcul->getResult();
    $numericResult = $result->getValue();
    

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27. 1 + 1
    

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28. Composition
    

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29. c
    a b
    a b
    

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30. a b c
    

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31. Higher-order functions
    

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32. Dependency Injection
    

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33. Inversion of control is really just a pretentious
    way of saying “Taking an argument”.
    – Rúnar Óli
    @runarorama
    

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34. Taking an argument
    

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35. g g’
    

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36. 0
    1
    2
    3
    4
    even?
    0
    2
    4
    

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37. 0
    1
    2
    3
    4
    #(+ 5 %)
    5
    7
    9
    6
    8
    

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38. 3
    6
    7
    9
    +
    0
    9
    25
    3
    16
    acumulator
    

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39. Datastructures
    

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40. Number 42
    String "Hello, cruel world."
    Map
    {:foo "bar",
    :baz "qux"}
    List [:a :b :c]
    Set
    #{"Arthur Dent"
    "Ford Prefect"}
    

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41. function is a means of
    abstraction
    

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42. data is a means of
    abstraction
    

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43. Structure
    Time & State
    

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44. Time & State
    

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45. Place-Oriented
    Programming
    

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50. identity
    

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51. new Foo("x") !== new Foo("x")
    

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52. defensive copy
    

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53. $users = new UserList();
    $users->add(new User("Igor"));
    notify($users);
    

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54. while (count($users)) {
    $user = $users->shift();
    notifyUser($user);
    }
    

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55. notify(clone $users)
    

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56. observation
    

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57. $user->getName()
    

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58. $user["name"]
    

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59. Value
    

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60. Primitives
    

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61. Value Object
    

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62. date address money
    response
    request
    

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63. serialization
    

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64. History
    

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65. Objects are forgetful
    

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66. $sophie->setName("Joanna")
    

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67. 2013-09-13 01:01:47 Sophie
    2013-09-13 01:02:25 Joanna
    2013-09-13 01:05:31 Caroline
    

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68. $joanna = $sophie->setName("Joanna")
    

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69. Git
    

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70. 98ca9 34ac2 f30ab
    master
    Snapshot A Snapshot B Snapshot C
    

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71. Epochal Time Model
    

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72. v1 v2 v3 v4
    f f f
    identity states
    events
    

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73. Lazy evaluation
    

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74. Iterator
    Generator
    Stream
    

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75. a
    b
    c
    d
    a’
    b’
    c’
    d’
    consume
    

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76. Order of execution
    becomes implicit
    

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77. ๏ filter
    ๏ map
    ๏ reduce
    

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78. What about I/O?
    

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79. Filesystem
    Database
    Network
    }is a place
    

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80. Separate I/O from
    computation
    

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82. What about testing?
    

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83. But I heard static
    methods are untestable
    and evil
    

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84. You cannot mock
    functions
    

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85. Why do we mock?
    

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86. Functions are fast
    

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87. Impure parts are
    mocked by passing
    functions
    

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88. my_beautiful_program(function () {
    return do_evil_shit();
    })
    

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89. Pure functions are
    inherently testable
    

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90. But functions make code
    look awkward!
    

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91. strlen(get_name(get_user($data)))
    

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92. $data |> get_user |> get_name |> strlen
    

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93. pipeline('get_user', 'get_name', 'strlen')
    

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94. But PHP does not properly
    support functions!
    

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95. use function igorw\edn\parse;
    $data = parse($edn);
    

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96. PHP 5.6 will hopefully
    get function autoloading
    

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97. Applicability of the
    functional paradigm
    

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98. f g
    h
    i
    j
    k
    l
    

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99. A
    foo
    foo
    foo
    foo
    B
    foo
    foo
    C
    foo
    foo
    D
    foo
    foo
    E
    foo
    foo
    

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100. Granularity
     

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102. Queue
     

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103. ๏ Value semantics
     ๏ Higher-order functions
     ๏ Lazy evaluation
     

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104. pure
     functions
     

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106. Questions?
     • joind.in/{ 9471, 9472 }
     • github.com/igorw/edn
     • github.com/nikic/iter
     • @igorwesome
     

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107. References
     • The Paradigms of Programming
     by Robert W. Floyd
     • Execution in the Kingdom of Nouns
     by Steve Yegge
     • The Value of Values
     by Rich Hickey
     • Are we there yet?
     by Rich Hickey
     

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