Java Wars VIII: The Function Awakens

Transcript

1. Grzegorz Piwowarek
   gpiwowarek@gmail.com
   

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2. GitHub, Twitter :: @pivovarit
   

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3. GitHub, Twitter :: @pivovarit
   VISIONS OF TONDAL.PL
   

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8. Why?
   

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9. //TODO:
   -lambda expressions
   -java.util.function
   -monad
   -java.util.Optional
   -java.util.stream.Stream
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10. lambda expressions
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11. lambda expressions
    (...) -> statement
    - Anonymous function
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12. lambda expressions
    x -> x + 1
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13. lambda expressions
    x -> x + 1
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    () -> 42
    

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14. lambda expressions
    x -> x + 1
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    () -> 42
    () -> {return 42;}
    

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15. lambda expressions
    x -> x + 1
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    () -> 42
    (x, y) -> {}
    () -> {return 42;}
    

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16. lambda expressions
    x -> x + 1
    - No type information
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17. method references
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18. java.util.function
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19. Function, BiFunction
    Consumer extends Function
    Supplier extends Function
    Predicate extends Function
    UnaryOperator extends Function
    BinaryOperator extends BiFunction
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20. Function, BiFunction
    Consumer extends Function
    Supplier extends Function
    Predicate extends Function
    UnaryOperator extends Function
    BinaryOperator extends BiFunction
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21. Function, BiFunction
    Consumer extends Function
    Supplier extends Function
    Predicate extends Function
    UnaryOperator extends Function
    BinaryOperator extends BiFunction
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22. Function, BiFunction
    Consumer extends Function
    Supplier extends Function
    Predicate extends Function
    UnaryOperator extends Function
    BinaryOperator extends BiFunction
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23. Function, BiFunction
    Consumer extends Function
    Supplier extends Function
    Predicate extends Function
    UnaryOperator extends Function
    BinaryOperator extends BiFunction
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24. MONAD
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25. GitHub, Twitter :: @pivovarit
    

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26. GOOGLE IMAGES...
    

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27. GOOGLE IMAGES...
    

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28. GOOGLE IMAGES...
    

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29. GOOGLE IMAGES...
    

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30. GOOGLE IMAGES...
    

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31. GOOGLE IMAGES...
    

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32. GOOGLE IMAGES...
    

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33. GOOGLE IMAGES...
    

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34. ...
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35. MONAD
    Design pattern
    http://got-steam.com/
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36. Why bother? :
    Boilerplate--
    Readability++
    Complexity--
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37. Imperative approach
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38. Declarative approach
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39. Generic type:
    "unit" method:
    "bind" method:
    MONAD
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40. Generic type:
    "unit" method:
    "bind" method:
    MONAD
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41. Generic type:
    "unit" method:
    "bind" method:
    MONAD
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42. Generic type:
    "unit" method:
    "bind" method:
    MONAD
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43. GitHub, Twitter :: @pivovarit
    

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44. GitHub, Twitter :: @pivovarit
    

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45. GitHub, Twitter :: @pivovarit
    

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46. http://www.ivanaborovnjak.com/project/box-in-a-box/
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47. Solution
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48. Monads in Java 8
    Optional
    Stream
    CompletableFuture
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49. Monads in Java 8
    Optional
    Stream
    CompletableFuture
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50. Optional
    Encapsulation of operations
    on optional values
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51. Optional
    Encapsulation of operations
    on optional values
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52. Optional
    type:
    "unit":
    "bind":
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53. Optional
    type: Optional
    "unit":
    "bind":
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54. Optional
    type: Optional
    "unit": Optional.ofNullable(), Optional.of()
    "bind":
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55. Optional
    type: Optional
    "unit": Optional.ofNullable(), Optional.of()
    "bind": Optional.flatMap(), Optional.map()
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56. Filtering an Optional
    .filter(Predicate)
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57. Unwrapping an Optional
    .get()
    .orElse(T default)
    .orElseGet(Supplier)
    .orElseThrow(Supplier)
    .ifPresent(Consumer)
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58. GitHub, Twitter :: @pivovarit
    http://theworryfreelife.com/wp-content/uploads/2015/08/comfort-zone.jpg
    

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59. Java 7 style
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60. Java 8 style
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61. Java 7,5 style ;)
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62. Java 7,5 style ;)
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63. GitHub, Twitter :: @pivovarit
    

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64. GitHub, Twitter :: @pivovarit
    

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65. Stream
    Encapsulation of operations
    on multiple items
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66. Stream
    type: Stream
    "unit": Stream.of(), Arrays.stream(), Collection.stream()
    "bind": Stream.flatMap()
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67. Stream
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68. Stream
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69. Stream
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70. Imperative vs. Declarative
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71. Imperative vs. Declarative
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72. Stream && Optional
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73. Stream
    lazy-initialized
    nonreusable
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74. intermediate operations
    .map()
    .flatMap()
    .filter()
    .peek()
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75. intermediate operations
    .map()
    .flatMap()
    .filter()
    .peek()
    Stream not consumed:
    does not print anything
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76. Consuming Stream
    .forEach(Consumer)
    .collect()
    .reduce(BinaryOperator)
    .allMatch(), anyMatch(), noneMatch()
    .findFirst(), findAny()
    .count()
    .toArray()
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77. Stream.reduce()
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78. Collectors
    .toList(), toMap(), toSet(), toCollection()
    .minBy(), maxBy()
    .joining()
    .partitioningBy()
    ...and many others
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79. Collectors.toList()
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80. Stream in APIs
    "any string".chars()
    Files.newDirectoryStream()
    Random.ints()
    ...
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81. you want more?
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82. github.com/
    TouK/ThrowingFunction
    http://www.javaslang.io/
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83. Thank You!
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84. REFERENCES:
    -"MONADIC JAVA" BY MARIO FUSCO
    -"WHAT'S WRONG WITH JAVA 8" BY PIERRE-YVES SAUMONT
    -WWW.ORACLE.COM
    -"A FISTFUL OF MONADS" - LEARN YOU A HASKELL FOR GREAT GOOD
    

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