Java Wars VIII: The Function Awakens

Transcript

1. Grzegorz Piwowarek gpiwowarek@gmail.com
2. GitHub, Twitter :: @pivovarit
3. GitHub, Twitter :: @pivovarit VISIONS OF TONDAL.PL
8. Why?
9. //TODO: -lambda expressions -java.util.function -monad -java.util.Optional -java.util.stream.Stream GitHub, Twitter :: @pivovarit
10. lambda expressions GitHub, Twitter :: @pivovarit
11. lambda expressions (...) -> statement - Anonymous function GitHub, Twitter :: @pivovarit
12. lambda expressions x -> x + 1 GitHub, Twitter :: @pivovarit
13. lambda expressions x -> x + 1 GitHub, Twitter :: @pivovarit () -> 42
14. lambda expressions x -> x + 1 GitHub, Twitter :: @pivovarit () -> 42 () -> {return 42;}
15. lambda expressions x -> x + 1 GitHub, Twitter :: @pivovarit () -> 42 (x, y) -> {} () -> {return 42;}
16. lambda expressions x -> x + 1 - No type information GitHub, Twitter :: @pivovarit
17. method references GitHub, Twitter :: @pivovarit
18. java.util.function GitHub, Twitter :: @pivovarit
19. Function<T, R>, BiFunction<T,U,R> Consumer<T> extends Function<T,Void> Supplier<T> extends Function<Void, T> Predicate<T> extends Function<T, Boolean> UnaryOperator<T> extends Function<T, T> BinaryOperator<T> extends BiFunction<T,T,T> GitHub, Twitter :: @pivovarit
20. Function<T, R>, BiFunction<T,U,R> Consumer<T> extends Function<T,Void> Supplier<T> extends Function<Void, T> Predicate<T> extends Function<T, Boolean> UnaryOperator<T> extends Function<T, T> BinaryOperator<T> extends BiFunction<T,T,T> GitHub, Twitter :: @pivovarit
21. Function<T, R>, BiFunction<T,U,R> Consumer<T> extends Function<T,Void> Supplier<T> extends Function<Void, T> Predicate<T> extends Function<T, Boolean> UnaryOperator<T> extends Function<T, T> BinaryOperator<T> extends BiFunction<T,T,T> GitHub, Twitter :: @pivovarit
22. Function<T, R>, BiFunction<T,U,R> Consumer<T> extends Function<T,Void> Supplier<T> extends Function<Void, T> Predicate<T> extends Function<T, Boolean> UnaryOperator<T> extends Function<T, T> BinaryOperator<T> extends BiFunction<T,T,T> GitHub, Twitter :: @pivovarit
23. Function<T, R>, BiFunction<T,U,R> Consumer<T> extends Function<T,Void> Supplier<T> extends Function<Void, T> Predicate<T> extends Function<T, Boolean> UnaryOperator<T> extends Function<T, T> BinaryOperator<T> extends BiFunction<T,T,T> GitHub, Twitter :: @pivovarit
24. MONAD GitHub, Twitter :: @pivovarit
25. GitHub, Twitter :: @pivovarit
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34. ... GitHub, Twitter :: @pivovarit
35. MONAD Design pattern http://got-steam.com/ GitHub, Twitter :: @pivovarit
36. Why bother? : Boilerplate-- Readability++ Complexity-- GitHub, Twitter :: @pivovarit
37. Imperative approach GitHub, Twitter :: @pivovarit
38. Declarative approach GitHub, Twitter :: @pivovarit
39. Generic type: "unit" method: "bind" method: MONAD GitHub, Twitter :: @pivovarit
40. Generic type: "unit" method: "bind" method: MONAD GitHub, Twitter :: @pivovarit
41. Generic type: "unit" method: "bind" method: MONAD GitHub, Twitter :: @pivovarit
42. Generic type: "unit" method: "bind" method: MONAD GitHub, Twitter :: @pivovarit
43. GitHub, Twitter :: @pivovarit
44. GitHub, Twitter :: @pivovarit
45. GitHub, Twitter :: @pivovarit
46. http://www.ivanaborovnjak.com/project/box-in-a-box/ GitHub, Twitter :: @pivovarit
47. Solution GitHub, Twitter :: @pivovarit
48. Monads in Java 8 Optional Stream CompletableFuture GitHub, Twitter :: @pivovarit
49. Monads in Java 8 Optional Stream CompletableFuture GitHub, Twitter :: @pivovarit
50. Optional Encapsulation of operations on optional values GitHub, Twitter :: @pivovarit
51. Optional Encapsulation of operations on optional values GitHub, Twitter :: @pivovarit
52. Optional type: "unit": "bind": GitHub, Twitter :: @pivovarit
53. Optional type: Optional<T> "unit": "bind": GitHub, Twitter :: @pivovarit
54. Optional type: Optional<T> "unit": Optional.ofNullable(), Optional.of() "bind": GitHub, Twitter :: @pivovarit
55. Optional type: Optional<T> "unit": Optional.ofNullable(), Optional.of() "bind": Optional.flatMap(), Optional.map() GitHub, Twitter :: @pivovarit
56. Filtering an Optional .filter(Predicate<T>) GitHub, Twitter :: @pivovarit
57. Unwrapping an Optional .get() .orElse(T default) .orElseGet(Supplier<T>) .orElseThrow(Supplier<Ex>) .ifPresent(Consumer<T>) GitHub, Twitter :: @pivovarit
58. GitHub, Twitter :: @pivovarit http://theworryfreelife.com/wp-content/uploads/2015/08/comfort-zone.jpg
59. Java 7 style GitHub, Twitter :: @pivovarit
60. Java 8 style GitHub, Twitter :: @pivovarit
61. Java 7,5 style ;) GitHub, Twitter :: @pivovarit
62. Java 7,5 style ;) GitHub, Twitter :: @pivovarit
63. GitHub, Twitter :: @pivovarit
64. GitHub, Twitter :: @pivovarit
65. Stream Encapsulation of operations on multiple items GitHub, Twitter :: @pivovarit
66. Stream type: Stream<T> "unit": Stream.of(), Arrays.stream(), Collection.stream() "bind": Stream.flatMap() GitHub, Twitter :: @pivovarit
67. Stream GitHub, Twitter :: @pivovarit
68. Stream GitHub, Twitter :: @pivovarit
69. Stream GitHub, Twitter :: @pivovarit
70. Imperative vs. Declarative GitHub, Twitter :: @pivovarit
71. Imperative vs. Declarative GitHub, Twitter :: @pivovarit
72. Stream && Optional GitHub, Twitter :: @pivovarit
73. Stream lazy-initialized nonreusable GitHub, Twitter :: @pivovarit
74. intermediate operations .map() .flatMap() .filter() .peek() GitHub, Twitter :: @pivovarit
75. intermediate operations .map() .flatMap() .filter() .peek() Stream not consumed: does not print anything GitHub, Twitter :: @pivovarit
76. Consuming Stream .forEach(Consumer<T>) .collect() .reduce(BinaryOperator<T>) .allMatch(), anyMatch(), noneMatch() .findFirst(), findAny() .count() .toArray() GitHub, Twitter :: @pivovarit
77. Stream.reduce() GitHub, Twitter :: @pivovarit
78. Collectors .toList(), toMap(), toSet(), toCollection() .minBy(), maxBy() .joining() .partitioningBy() ...and many others GitHub, Twitter :: @pivovarit
79. Collectors.toList() GitHub, Twitter :: @pivovarit
80. Stream in APIs "any string".chars() Files.newDirectoryStream() Random.ints() ... GitHub, Twitter :: @pivovarit
81. you want more? GitHub, Twitter :: @pivovarit
82. github.com/ TouK/ThrowingFunction http://www.javaslang.io/ GitHub, Twitter :: @pivovarit
83. Thank You! GitHub, Twitter :: @pivovarit
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