Programming across paradigms

Presented at PolyConf 2017: https://polyconf.com/

The programming paradigm we work in shapes every aspect of how we craft our code, providing a model of what a program is, and what it can and should be. In this talk, we’ll explore the connections between the programs we write, the languages we work in, and the paradigms we use, and try to get some historical and philosophical perspective on the familiar paradigms of imperative, declarative, object-oriented, and functional programming, focusing on the points where they intersect and collide. We’ll discover the valuable lessons different paradigms can teach us, and find motivation to stop arguing with our fellow coders about which is superior, and instead encourage each other - as individuals and a community - to pursue poly-paradigm programming.

Transcript

1. programming across paradigms @AnjanaVakil PolyConf 2017
2. hi, I’m @AnjanaVakil! The Recurse Center
3. 1978 ACM Turing Award Lecture
4. “I believe the best chance we have to improve the general practice of programming is to attend to our paradigms.” Robert W. Floyd “The paradigms of programming.”, 1979. p. 456
5. what is a paradigm?
6. Front cover of 1st edition paperback (1962), via Wikimedia
7. a paradigm is a worldview
8. a paradigm is a model
9. “All models are wrong” George E. P. Box "Robustness in the strategy of scientific model building", 1979, p. 202.
10. “In learning a paradigm the scientist acquires theory, methods, and standards together, usually in an inextricable mixture.” Thomas S. Kuhn The Structure of Scientific Revolutions, (2nd ed.) 1970. p. 109.
11. theory what entities make up the universe how they behave and interact
12. methods & standards which problems are worth solving which solutions are legitimate
13. a paradigm enables progress
15. paradigm
16. Scenography of the Ptolemaic cosmography by Loon, J. van (Johannes), ca. 1611–1686. via Wikimedia
17. paradigm anomaly
18. paradigm anomaly crisis
19. paradigm anomaly crisis shift
20. Scenographia Systematis Copernicani (The Copernican System), 1686. via Wikimedia
21. paradigm anomaly crisis shift
22. what is programming?
24. imperative programming follow my commands in the order I give them remember state
25. imperative programming “Clocks Gears Wallpaper” via Wallpoper
26. object-oriented programming keep your state to yourself receive my messages respond as you see fit
27. object-oriented programming “Slide of the Week: Increased WBC, April 14, 2011” via Center for Genomic Pathology
28. functional programming mutable state is dangerous pure functions are safe data goes in data comes out
29. functional programming “2012 Chevrolet Cruze on the production line at Lordstown Assembly in Lordstown, Ohio” via GM
30. declarative programming these are the facts this is what i want i don’t care how you do it
31. declarative programming “Sudoku05” by Jelte (CC BY-SA 3.0) via Wikimedia
32. https://www.info.ucl.ac.be/~pvr/paradigms.html
33. are they really so different?
34. shared mutable state
35. shared mutable state
36. shared mutable state
37. shared mutable state
38. “I'm sorry that I long ago coined the term "objects" for this topic because it gets many people to focus on the lesser idea. The big idea is "messaging".” Alan Kay Message to Smalltalk/Squeak mailing list, 1998
39. message ↓ response
40. input ↓ output
41. behavior
42. Lambda calculus TRUE := λx.λy.x FALSE := λx.λy.y Smalltalk class True ifTrue: a ifFalse: b ^ a value class False ifTrue: a ifFalse: b ^ b value
43. which paradigm is The Best?
44. “All models are wrong… George E. P. Box "Robustness in the strategy of scientific model building", 1979, p. 202.
45. “All models are wrong but some are useful” George E. P. Box "Robustness in the strategy of scientific model building", 1979, p. 202.
47. “Is the model true?” “Is the model illuminating and useful?” George E. P. Box "Robustness in the strategy of scientific model building", 1979, p. 202.
48. what can a paradigm illuminate?
49. be explicit focus on implementation be machine-efficient
50. Rust for Elixir: NIFty! #[macro_use] extern crate rustler; #[macro_use] extern crate rustler_codegen; #[macro_use] extern crate lazy_static; use rustler::{NifEnv, NifTerm, NifResult, NifEncoder}; mod atoms { rustler_atoms! { atom ok; } } rustler_export_nifs! { "Elixir.Testing.MyNif", [("add", 2, add)], None } fn add<'a>(env: NifEnv<'a>, args: &[NifTerm<'a>]) -> NifResult<NifTerm<'a>> { let num1: i64 = args[0].decode()?; let num2: i64 = args[1].decode()?; // complicated math here // such imperative, so performance, wow Ok((atoms::ok(), result).encode(env)) } Adapted from H.E.B. Josephsen, “Elixir FFI with Rust”, PolyConf 2017.
51. be abstract focus on domain be human-efficient
52. Embedded DSL in Java cal = new Calendar(); cal.event("PolyConf") .on(2017, 07, 09) .from("09:00") .to("19:00") .at("La Géode"); Adapted from M. Fowler & R. Parsons, Domain Specific Languages, 2011, p. 345.
53. encapsulate remember
54. Context-aware API in F# module MyApi = let fnA dep1 dep2 dep3 arg1 = doAWith dep1 dep2 dep3 arg1 let fnB dep1 dep2 dep3 arg2 = doBWith dep1 dep2 dep3 arg2 type MyParametricApi(dep1, dep2, dep3) = member __.FnA arg1 = doAWith dep1 dep2 dep3 arg1 member __.FnB arg2 = doBWith dep1 dep2 dep3 arg2 Adapted from E. Tsarpalis, “Why OOP Matters (in F#)”, 2017.
55. isolate transform
56. Adapted from J. Kerr, “Why Functional Matters: Your white board will never be the same”, 2012. Functional program flow
57. Each paradigm supports a set of concepts that makes it the best for a certain kind of problem. Peter Van Roy “Programming paradigms for dummies: What every programmer should know”, 2009, p. 10.
58. no paradigm is best absolutely each is best for a certain case
59. multi-paradigm languages give you options
60. what’s the point?
61. paradigms enable programming
62. paradigms define programming
63. embrace your paradigm, don’t fight it
64. be open to shift
65. “If the advancement of the general art of programming requires the continuing invention and elaboration of paradigms...” Robert W. Floyd “The paradigms of programming.”, 1979. p. 456
66. “... advancement of the art of the individual programmer requires that [t]he[y] expand [their] repertory of paradigms.” Robert W. Floyd “The paradigms of programming.”, 1979. p. 456
67. learn new paradigms invent new paradigms
68. let’s attend to our paradigms
69. David Albert, Darius Bacon, Julia Evans & the Recurse Center PolyConf organizers thank you! @AnjanaVakil
70. References & further reading/watching Box, George E.P. (1979), "Robustness in the strategy of scientific model building", in Launer & Wilkinson, Robustness in Statistics, Academic Press, pp. 201–236. Cook, William (2012). “A Proposal for Simplified, Modern Definitions of ‘Object’ and ‘Object Oriented’”. wcook.blogspot.fr/2012/07/proposal-for-simplified-modern.html Floyd, Robert W. (1979). “The paradigms of programming.” Commun. ACM 22, 8, 455-460. Fowler, Martin, with Parsons, Rebecca. (2011). Domain Specific Languages. Addison-Wesley. Josephsen, Hans Elias Bukholm (2017). “Elixir FFI with Rust”, PolyConf. http://slides.com/hansihe/rustler#/ Kay, Alan (1998). Message to Smalltalk/Squeak mailing list. wiki.c2.com/?AlanKayOnMessaging Kerr, Jessica (2012). “Why Functional Matters: Your white board will never be the same”. blog.jessitron.com/2012/06/why-functional-matters-your-white-board.html Kerr, Jessica (2014). “Functional Principles for Object-Oriented Development”, GOTO Chicago. https://youtu.be/GpXsQ-NIKXY Kuhn, Thomas S. (1970). The Structure of Scientific Revolutions. (2nd ed.). University of Chicago Press. Tsarpalis, Eirik. (2017). “Why OO matters (in F#)”. https://eiriktsarpalis.wordpress.com/2017/03/20/why-oo-matters-in-f/ Van Roy, Peter. (2009). “Programming paradigms for dummies: What every programmer should know.” In New computational paradigms for computer music, p. 104. Williams, Ashley. (2015). “If you wish to learn ES6/2015 from scratch, you must first invent the universe”, JSConf. https://youtu.be/DN4yLZB1vUQ