FP vs. OOP: Beyond the Bikeshed

In object-oriented languages like Ruby, people often say that “everything is an object”—but first-class functions have become standard for object-oriented languages too. C# has had them and other related features for years, and even Java is in the game these days! Some“functional” languages seem to have some very object-oriented-looking features, too. If that sounds wrong to you, let's talk about polymorphism and more in languages like Clojure, Elixir, and even Haskell! So where does object-oriented programming (OOP) end and functional programming (FP) begin?

In this session, we'll look at these programming paradigms with a more critical eye, focusing on where FP and OOP folks fundamentally disagree, where these paradigms have more in common than the industry's rhetoric suggests, and how we can use those insights to make better decisions about the software we build.

Transcript

1. 8th Light, Inc. FP vs. OOP: Beyond the Bikeshed Colin Jones @trptcolin https://8thlight.com
2. agenda bikesheds definitions details conclusions
3. bikesheds
4. 8th Light, Inc. Bikeshed picture
5. C. Northcote Parkinson
6. Parkinson’s Law of Triviality
7. committee meeting / argument picture
8. 8th Light, Inc. Nuclear plant picture
9. 8th Light, Inc. Bike shed picture
10. bikesheds
12. http://bikeshed.com/
13. http://bikeshed.com/
14. http://bikeshed.com/
15. http://bikeshed.com/
16. FP vs. OOP
17. axes of antipathy
18. dynamic vs. static
19. threads vs. processes
20. vertical scaling vs. horizontal scaling
21. synchronous vs. asynchronous
22. convention vs. configuration
23. easy vs. simple
24. we could go on…
25. what’s to be done?
26. FP vs. OOP
27. FP’ers say…
28. OOP is overcomplicated: dozens of classes for the simplest task FP’ers say:
29. OOP means a big ball of mud FP’ers say:
30. It’s impossible to use OOP well FP’ers say:
31. FP is about making systems easier to understand FP’ers say:
32. FP is for everybody FP’ers say:
33. OOP’ers say…
34. FP is concrete dependencies everywhere, needlessly convoluted, callback hell OOP’ers say:
35. FP is concrete dependencies everywhere, needlessly convoluted, callback hell OOP’ers say:
36. FP is concrete dependencies everywhere, needlessly convoluted, callback hell OOP’ers say:
37. You have to be really smart to use FP well OOP’ers say:
38. OOP is about making systems easier to understand OOP’ers say:
39. OOP is for everybody OOP’ers say:
40. whew
41. definitions
42. OOP
43. classes and objects OOP
44. inheritance, polymorphism, and encapsulation OOP
45. "OOP to me means only messaging, local retention and protection and
 hiding of state-process, and extreme late-binding of all things.” - Alan Kay OOP
46. "OOP to me means only messaging, local retention and protection and
 hiding of state-process, and extreme late-binding of all things.” - Alan Kay OOP
47. "OOP to me means only messaging, local retention and protection and
 hiding of state-process, and extreme late-binding of all things.” - Alan Kay OOP
48. "OOP to me means only messaging, local retention and protection and
 hiding of state-process, and extreme late-binding of all things.” - Alan Kay OOP
49. FP
50. programming with mathematical functions FP
51. first-class functions FP
52. avoiding side effects FP
53. immutability FP
54. avoiding side causes FP
55. whew
56. details
57. languages
58. Java C# Ruby Python JavaScript Haskell Clojure Elixir Erlang Scala
59. features
60. 8th Light, Inc. Volkswagen bug picture
61. FP features
62. first-class functions FP
63. first-class functions FP OOP
64. laziness FP FP
65. laziness FP FP OOP
66. persistent data structures / immutability FP FP
67. persistent data structures / immutability FP FP OOP
68. OOP features
69. classes OOP
70. namespacing OOP
71. namespacing OOP FP
72. data containment OOP
73. data containment OOP FP
74. messaging OOP
75. messaging OOP FP
76. polymorphism OOP
77. polymorphism OOP FP
78. encapsulation OOP
79. encapsulation OOP FP
80. state management OOP
81. state management OOP FP
82. inheritance OOP
83. inheritance OOP FP?
84. inheritance OOP? FP?
85. unique features
86. pattern matching FP
87. reified effects? FP
88. tail recursion optimization FP
89. 1-letter variable names? FP
90. 1-letter variable names? FP? OOP?
91. OOP classes and objects
92. OOP 3000-line files?
93. 3000-line files? FP OOP
94. features?
95. constraints
96. avoid side effects avoid side causes FP
97. OOP avoid doing all the work avoid exposing internals avoid concrete dependencies
98. conclusions
99. emphasis
100. OOP messaging encapsulation polymorphism
101. explicit causes & explicit effects FP
102. FP and OOP are mostly orthogonal choices
103. plurality
104. focus
105. extrapolating
106. precision
107. charity
108. more • Parkinson’s Law of Triviality: https://www.farnamstreetblog.com/2013/12/ parkinsons-law/ • How the term “bikeshed" got into software: http://bikeshed.com • Alan Kay’s definition of OOP: http://www.purl.org/stefan_ram/pub/ doc_kay_oop_en • Kris Jenkins, “What is Functional Programming”: http://blog.jenkster.com/ 2015/12/what-is-functional-programming.html • Stuart Halloway, “Simplicity Made Easy”: https://youtu.be/cidchWg74Y4 • John Hughes, “Why Functional Programming Matters”: https:// www.cs.kent.ac.uk/people/staff/dat/miranda/whyfp90.pdf
109. more • Gamma/Helm/Johnson/Vlissides (Gang of Four), Design Patterns: http://a.co/ 6OdEq4h • Chris Okasaki, Purely Functional Data Structures: http://a.co/isBRerv • Gary Bernhardt, “Boundaries”: https://www.destroyallsoftware.com/talks/ boundaries • Peter van Roy and Seif Haridi, Concepts, Techniques, and Models of Computer Programming: https://www.info.ucl.ac.be/~pvr/book.html • Gary Bernhardt, “Ideology”: https://www.destroyallsoftware.com/talks/ideology
110. 8th Light, Inc. Thank you! Colin Jones @trptcolin https://8thlight.com