Dimitry Solovyov - The imminent threat of functional programming
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The document discusses the threat of functional programming becoming more widely adopted. It begins by introducing the author and their background in functional programming. It then contrasts imperative programming which focuses on sequencing instructions and memory management, with declarative programming which describes what is wanted without specifying how to do it. The document advocates for the benefits of functional programming such as its focus on minimizing side effects and moving parts to make code more understandable. It discusses concepts in functional programming including higher order functions, immutable data structures, and avoiding object encapsulation. Finally, it provides a checklist for exploring functional programming further.
Dimitry Solovyov - The imminent threat of functional programming
- 1. The Imminent Threat of Functional Programming
- 2. Dimitry Solovyov ‣ Haskell enthusiast and FP proponent ‣ Heavy user of Underscore (FP library for JavaScript) ‣ Former assistant teacher of FP course at TTI ‣ Developer at Amber Games and Livesheets
- 5. In programming land, there are two kinds of problems
- 6. In programming land, there are two kinds of problems memory management
- 7. In programming land, there are two kinds of problems sequencing memory (aka do it in what order?) management
- 8. In programming land, there are two kinds of problems sequencing memory E D LV management (aka do it in what order?) SO
- 9. In programming land, there are two kinds of problems memory D * sequencing VE (aka do it in what order?) O L management S * Except for null pointer exceptions ;-)
- 10. In programming land, there are two kinds of problems ? memory D * sequencing VE (aka do it in what order?) O L management S * Except for null pointer exceptions ;-)
- 11. Sequencing in Java while cond stmt do stmt while cond for init cond step stmt for x : xs stmt
- 12. Sequencing in Ruby loop stmt while cond stmt until cond stmt stmt while cond stmt until cond for x in xs stmt xs each stmt n times stmt n upto m stmt n downto m stmt ...
- 13. Sequencing in Ruby loop stmt while cond stmt How elegant! until cond stmt stmt while cond stmt until cond for x in xs stmt xs each stmt n times stmt n upto m stmt n downto m stmt ...
- 14. Imperative programming in a nutshell 10 BEGIN 20 DO SOMETHING 30 40 DO THAT OTHER THING GOTO 20 ✔ INSTRUCTIONS RESULT
- 15. Declarative programming in a nutshell Dear computer, I want a pony. MAGIC ✔ DESCRIPTION RESULT
- 16. INSTANT SUCCESS
- 17. “ OO makes code understandable by encapsulating moving parts. FP makes code understandable by minimizing moving parts. ” -- Michael Feathers “Functional Programming in C++” http://goo.gl/aVSXX
- 18. Abstraction and reusability in FP Absolutely abstract Category theory * ly reu sable High Exciting ly comp osable Mathematically proven Ex tremely fun to be composable * Check out Scalaz for CT in Scala Guava for other FP patterns in Java
- 19. + Some GoF pattern analogs provided at semantic level “Design Patterns in Haskell” http://goo.gl/T0Evt
- 20. You can get away without encapsulating in objects Data types fo rm r fo ed d ne in to ig s de operate on Immutable Combinators data structures
- 21. You can get away without encapsulating in objects Data types fo rm r fo ed d ne in to ig s de operate on Immutable Combinators data structures
- 22. You can get away without encapsulating in objects Data types Ready for the age of multicore fo rm r fo ed d ne in to ig s de operate on Immutable Combinators data structures
- 23. Traits instead of inheritance Thesis: Inheriting state creates brittle software. Inheriting implementation tends to become useless over time. “Life without Objects” http://goo.gl/wlOyq
- 24. Traits instead of inheritance Thesis: Inheriting state creates brittle software. Inheriting implementation tends to become useless over time. A B Data type “Life without Objects” C Expected to behave like A, B, and C http://goo.gl/wlOyq
- 25. “ In the exclusive sense, functional means no side-effects. In the inclusive sense it means a programming style which composes functions in interesting ways. ” -- Martin Odersky “In Defense of Pattern Matching” http://goo.gl/HaKQD
- 26. Origin of the “functional style” LISP ML Common Lisp Standard ML Scheme OCaml Dylan F# Racket Haskell Closure JVM Frege JVM Scala * JVM * (cough) Close enough.
- 27. LISP ML Dynamic Strong types Code = data Type inference Metaproggin' ADTs First-class functions Higher-order functions Pattern matching
- 28. LISP ML Dynamic Strong types Code = data Type inference Metaproggin' ADTs First-class functions Higher-order functions Pattern matching
- 29. Linus says: “Words are cheap, show me the code.”
- 30. Fake first-class functions in Java interface Func<A, B> { B apply(A x); } static <A, B, C> Func<A, C> compose(final Func<A, B> f, final Func<B, C> g) { return new Func<A, C>() { public C apply(A x) { return g.apply(f.apply(x)); } }; }
- 31. Fake higher-order functions in Java static <A, B> List<B> map(final Iterable<A> xs, final Func<A, B> f) { List<B> ys = new ArrayList<B>(); for (A x : xs) { B y = f.apply(x); ys.add(y); } return ys; } map
- 32. Fake higher-order functions in Java static <A, B> B fold(final Iterable<A> xs, final B init, final Func2<A, B, B> f) { B acc = init; for (A x : xs) { acc = f.apply(x, acc); } return acc; } fold
- 34. How logic works x=1 y=2 x+y=3
- 35. in languages How logic works with side-effects x=1 y=2 x + y = 3* * But only if the moon is still young! Otherwise the answer is 5.
- 36. Functional programming on the JVM en l fe d tio ss ar ia ef le ch n c o cy s nc cla sp nt es at er e- rol ct ns g an re in ur m att fu st- sid nt tr efe os p fir cl r Clojure ✔ ✔ ✔ ✘ ✘ Fantom ✔ ✔ ✔ ✘ ✘ Frege ✔ ✔ ✔ ✔ ✔ Java ✔ ✘ ✘ ✘ ✘ JRuby ✔ ✘ ✘ ✘ ✘ Kotlin ✔ ✔ ✔ ✘ ✔ Scala ✔ ✔ ✔ ✘ ✔
- 37. FP exploration checklist ❏ Start learning a functional language: Scala, Clojure, or even Haskell ❏ Get together @ Latvian FP Group: look for it on LinkedIn http://goo.gl/YhlJl ❏ Talk to me! [email protected]