The document discusses functional programming concepts like immutability, higher order functions, and lazy evaluation. It provides examples of map, filter and reduce functions in Clojure and how they can be used to transform data. The document also discusses decomposing problems into smaller subproblems and combining the solutions using functional techniques. It advocates applying a functional mindset and combining functional and object-oriented approaches.

1. impactos no design
com programação
funcional
Luiz Costa
@gutomcosta
www.sagadoprogramador.com.br
Sunday, October 20, 13

2. Sunday, October 20, 13

3. Programação Funcional?
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4. Programação Funcional?
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5. Programação Funcional?
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6. Programação Funcional?
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7. Programação Funcional?
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8. Programação Funcional?
e alguns novatos
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9. orientação a objetos
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10. Sunday, October 20, 13

11. conjunto de ideias
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12. conjunto de ideias
encapsulamento
polimorfismo
objetos
herança
estado ...
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13. programação funcional
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14. Sunday, October 20, 13

15. conjunto de ideias
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16. conjunto de ideias
funções
higher-order functions
imutabilidade
lazy evaluation
recursão ...
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17. código imperativo
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18. código imperativo
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19. código imperativo
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20. código imperativo
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21. código imperativo
Foco no “como fazer”
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22. código declarativo
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23. código declarativo
Foco no “o que fazer”
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24. código declarativo
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25. código declarativo
Foco no “o que fazer”
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26. “When writing a modular program to solve a problem,
one first divides the problem into subproblems, then
solves the subproblems, and finally combines the
solutions. The ways in which one can divide up the
original problem depend directly on the ways in which
one can glue solutions together.”
“Why functional programming matters”
-John Hughes in Research topics in functional programming, 1990
Sunday, October 20, 13

27. “When writing a modular program to solve a problem,
one first divides the problem into subproblems, then
solves the subproblems, and finally combines the
solutions. The ways in which one can divide up the
original problem depend directly on the ways in which
one can glue solutions together.”
“Why functional programming matters”
-John Hughes in Research topics in functional programming, 1990
Sunday, October 20, 13

28. “When writing a modular program to solve a problem,
one first divides the problem into subproblems, then
solves the subproblems, and finally combines the
solutions. The ways in which one can divide up the
original problem depend directly on the ways in which
one can glue solutions together.”
“Why functional programming matters”
-John Hughes in Research topics in functional programming, 1990
Sunday, October 20, 13

29. ..argue in the remainder of this paper that functional
languages provide two new, very important kinds of
glue.
higher order function
lazy evaluation
“Why functional programming matters”
-John Hughes in Research topics in functional programming, 1990
Sunday, October 20, 13

30. building blocks
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31. Sunday, October 20, 13

32. uma variável?
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33. uma variável?
first class functions
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34. Sunday, October 20, 13

35. invocando uma função
função como parâmetro
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36. invoca a função
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37. Sunday, October 20, 13

38. dados e funções separados
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39. dados e funções separados
mesma função variando comportamento
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40. higher order function
uma funcão que recebe outra função como
argumento ou retorna uma função
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41. functional style
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42. OO foco na estrutura
Como substituir uma implementação em
runtime?
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43. FP foco na transformação
transformação?
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44. listas, map, reduce, filter
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45. map
Text
Text
Text
Text
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46. map
clojure.string
Text
Text
Text
Text
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47. map
clojure.string
jose
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Text
Text
Text
Textluiz
paulo

48. map
clojure.string
jose
capitalize
Jose
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Text
Text
Text
Textluiz
paulo

49. map
clojure.string
jose
Text
Text
Text
Textluiz
paulo
capitalize
Jose
Sunday, October 20, 13
capitalize
Paulo

50. map
clojure.string
jose
Text
Text
Text
Textluiz
paulo
capitalize
capitalize
Jose
Sunday, October 20, 13
capitalize
Paulo
Luiz

51. focus on results, not
steps
“Functional Thinking”
-Neal Ford - IBM Developer Works series
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52. Filter
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clojure.string

53. Filter
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clojure.string

54. Filter
1
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2
3
4
5
clojure.string
6
7
8
9

55. Filter
1
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2
3
4
5
clojure.string
6
7
8
9

56. Filter
1
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2
3
4
5
clojure.string
6
7
8
9

57. Filter
1
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2
3
4
5
clojure.string
6
7
8
9

58. Filter
1
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2
3
4
5
clojure.string
6
7
8
9

59. Filter
1
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2
3
4
5
clojure.string
6
7
8
9

60. Filter
1
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2
3
4
5
clojure.string
6
7
8
9

61. Filter
1
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2
3
4
5
clojure.string
6
7
8
9

62. Filter
1
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2
3
4
5
clojure.string
6
7
8
9

63. Filter
1
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2
3
4
5
clojure.string
6
7
8
9

64. Filter
1
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2
3
4
5
clojure.string
6
7
8
9

65. Reduce
0
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10
20
30
40

66. Reduce
função
0
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10
20
30
40

67. Reduce
função
100
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68. Argentum
Análise de Candlesticks, bolsa de valores
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69. Candlesticks
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70. Argentum
Domain Model
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71. antes, um pouco de
clojure
muito pouco mesmo ...
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72. Clojure
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73. Clojure
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74. Clojure
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75. Clojure
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76. Clojure
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77. Clojure
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78. como representar os
conceitos?
Negócio, Candlestick
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79. Sunday, October 20, 13

80. Sunday, October 20, 13

81. Sunday, October 20, 13

82. define uma abstração
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83. Sunday, October 20, 13

84. dados e funções separados
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85. dados e funções separados
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86. decompose an algorithm into functions that are
simple, meaningful and useful.
“Tutorial on Good Lisp Programming Style”
-Peter Norvig in 1992
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87. decompose an algorithm into functions that are
simple, meaningful and useful.
“Tutorial on Good Lisp Programming Style”
-Peter Norvig in 1992
Sunday, October 20, 13

88. decomposição
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89. decomposição
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90. invariantes
decomposição
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91. decomposição
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92. decomposição
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93. decomposição
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94. decomposição
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95. dependência de outro
namespace
decomposição
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96. Argentum
Geração de gráfico com indicadores
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97. Argentum
Geração de gráfico com indicadores
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define uma
abstração

98. Argentum
Geração de gráfico com indicadores
define uma
abstração
define comportamentos diferentes
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99. como variar o
comportamento?
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100. declara as funções
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101. compondo funções
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102. decomposição de função
compondo funções
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103. higher order functions
compondo funções
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104. calculando a média móvel
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105. calculando a média móvel
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106. calculando a média móvel
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107. calculando a média móvel
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108. com diferentes
building blocks, é
preciso repensar as
decisões de design
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109. OO e FP Juntos?
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110. Functional in the small, OO in the large.
“Tell Above, and Ask Below - Hybridizing OO and Functional design”
-Michael Feathers, blog post
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111. Functional Core, imperative shell.
“Destroy all soft ware - episode 72”
-Gary Bernhardt, destroy on soft ware screen cast series
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112. conclusão
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113. Functional Programming is more
a mindset than a particular set
of tools or languages.
“Functional Thinking”
-Neal Ford - IBM Developer Works series
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114. Obrigado
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115. Referências
SICP - http://mitpress.mit.edu/sicp/full-text/book/book.html
Why functional programming matters - http://www.cs.kent.ac.uk/people/staff/dat/miranda/whyfp90.pdf
Clojure - http://clojure.org/
Functional Thinking - http://www.ibm.com/developerworks/java/library/j-ft1/index.html
Tell Above, and ask Below - http://michaelfeathers.typepad.com/michael_feathers_blog/2012/03/
tell-above-and-ask-below-hybridizing-oo-and-functional-design.html
Functional Core, imperative shell - https://www.destroyallsoftware.com/screencasts/catalog/
functional-core-imperative-shell
Tutorial on good lisp programming style - http://www.cs.umd.edu/~nau/cmsc421/norvig-lispstyle.pdf
Sunday, October 20, 13