Embrace the static. Cherish the functional. Remain a Rubyist.

Slides from a presentation delivered on 03.03.2013 at wroc_love.rb 2013.

Video: https://www.youtube.com/watch?v=P6_illGY_00

Transcript

1. Embrace the static Cherish the functional Remain a Rubyist
2. My name is Jan Stępień and I come from Warsaw
3. Table of contents 1. The part with code on slides 2. The part without code on slides
4. Ruby The quintessence of object orientation Um, no.
5. So, Ruby was a Lisp originally, in theory. Let’s call it MatzLisp from now on. Matz Re: Ruby’s lisp features 2006 http://www.flickr.com/photos/rrrodrigo/2394121442
6. Array #collect a.k.a. map #inject a.k.a. reduce #select a.k.a. filter
7. We ♥ blocks File.open(”.gitignore”, ”a”) do |f| f.write wordlist.select do |word| word.is_rude? end end
8. We ♥ blocks describe ”Piece of code” do context ”with plenty of blocks” do it ”is probably Ruby” do code.should be_kind_of(Ruby) end end end
9. class LanguageEcosystem def ⇝(other) self.inspired? other end end
10. Lisp ⇝ Ruby
11. Observation no. 1 Ruby is inspired by Lisp
12. Ruby ⇝ ?
13. Case in point no. 1 Rack
14. require ’rack’ def app(env) [ 200, {”Content-Type” => ”text/plain”}, [”Hello, Rack!”] ] end Rack::Handler::WEBrick.run method(:app), Port: 9292
15. (use ’ring.adapter.jetty) (defn app [req] { :status 200 :headers {”Content-Type” ”text/plain”} :body ”Hello, Ring!” } ) (run-jetty app {:port 9292})
16. (use ’ring.adapter.jetty) (defn app [req] {:status 200 :headers {”Content-Type” ”text/plain”} :body ”Hello, Ring!”}) (run-jetty app {:port 9292}) Ruby ⇝ Clojure
17. Case in point no. 2 RSpec
18. require ”rspec” describe ”Plus operator” do context ”when adding doubles” do it ”returns a sum” do (1.5 + 2.5).should == 4 end end end
19. import Test.Hspec main = hspec $ do describe ”Plus operator” $ do context ”when adding doubles” $ do it ”returns a sum” $ do 1.5 + 2.5 ‘shouldBe‘ 4 Ruby ⇝ Haskell
20. Observation no. 2 Solutions present in Ruby are reused elsewhere
21. omg ruby is so awesome!!1!∗ ∗ Still, that’s not far from the truth.
22. http://www.flickr.com/photos/39747297@N05/5229733311
23. http://www.flickr.com/photos/mikebaird/3898808431
24. http://www.flickr.com/photos/39747297@n05/5229733311
25. http://www.flickr.com/photos/riveredgedental/7189878275
26. Let’s talk about testing
27. describe ”Divison of doubles” do it ”returns a quotient” do (1.5 / 3.0).should == 0.5 end end
28. describe ”Divison of doubles” do it ”returns a quotient” do floats = 1.upto(5).map &:to_f floats.each do |x| floats.each do |y| ((x / y) * y).should == x end end end end
29. 1.0 / 0.0 http://www.flickr.com/photos/dailoshane/4470995198
30. main = hspec $ do describe ”Division of doubles” $ do it ”returns a quotient” $ do 1.5 / 3.0 ‘shouldBe‘ 0.5
31. main = hspec $ do describe ”Division of doubles” $ do it ”returns a quotient” $ do property (\a b -> (a / b) * b == a)
32. Division of doubles - returns a quotient FAILED [1] 1) Division of doubles returns a quotient FAILED *** Failed! Falsifiable (after 1 test): 0.0 0.0 Finished in 0.0023 seconds 1 example, 1 failure
33. main = hspec $ do describe ”Division of doubles” $ do it ”returns a quotient” $ do property (\a b -> (a / b) * b == a)
34. main = hspec $ do describe ”Division of doubles” $ do it ”returns a quotient” $ do property (\a b -> b /= 0 ==> (a / b) * b == a)
35. Division of doubles - returns a quotient FAILED [1] 1) Division of doubles returns a quotient FAILED *** Failed! Falsifiable (after 4 tests): 3.0 2.7716 Finished in 0.0271 seconds 1 example, 1 failure
36. $ ghci Prelude> (3.0 / 2.7716) * 2.7716 3.0000000000000004 $ irb irb(main):001:0> (3.0 / 2.7716) * 2.7716 => 3.0000000000000004
37. QuickCheck
38. gem install rushcheck
39. include RushCheck prop = Assertion.new(Float, Float) do |x, y| (x / y) * y == x end prop.check $ ruby -rrushcheck divide.rb Falsifiable, after 5 tests: [-1.5, 0.0]
40. include RushCheck prop = Assertion.new(Float, Float) do |x, y| guard { y != 0 } (x / y) * y == x end prop.check $ ruby -rrushcheck divide.rb Falsifiable, after 33 tests: [12.923076923076923, 10.909090909090908]
41. Haskell ⇝ Ruby
42. Observation no. 3 Ideas from Haskell work great in Ruby
43. Let’s talk about concurrency
44. Erlang Rock-solid virtual machine Comprehensive standard library
45. spawn link ! receive
46. Erlang and First-Person Shooters Malcolm Dowse, 2011
47. Erlang at Facebook Eugene Letuchy, 2009
48. gem install celluloid
49. class Capital def decapitalize ”We’re disappointed” end end $ irb irb(main)> warsaw = Capital.new => #<Capital:0x00000002b4f530> irb(main)> warsaw.decapitalize => ”We’re disappointed”
50. class Capital include Celluloid attr_reader :capital def initialize @capital = true end def decapitalize @capital = false ”We’re disappointed” end end
51. $ irb irb(main)> warsaw = Capital.spawn => #<Celluloid::Actor(Capital:0x18caf2c)> irb(main)> warsaw.decapitalize => ”We’re disappointed” irb(main)> warsaw.capital => false
52. $ irb irb(main)> warsaw = Capital.spawn => #<Celluloid::Actor(Capital:0x18caf2c)> irb(main)> warsaw.decapitalize! => nil irb(main)> warsaw.capital => false
53. class Capital include Celluloid attr_reader :capital def initialize @capital = true end def decapitalize raise ”Over our dead bodies” end end
54. $ irb irb(main)> warsaw = Capital.spawn => #<Celluloid::Actor(Capital:0x18caf2c)> irb(main)> warsaw.decapitalize RuntimeError: Over our dead bodies capital.rb:11:in ‘decapitalize’
55. $ irb irb(main)> warsaw = Capital.spawn => #<Celluloid::Actor(Capital:0x18caf2c)> irb(main)> warsaw.decapitalize! RuntimeError: Over our dead bodies capital.rb:11:in ‘decapitalize’ => nil
56. class Capital include Celluloid def decapitalize raise ”Over our dead bodies” end end class City include Celluloid trap_exit :actor_died def actor_died(actor, reason) puts ”#{actor.inspect} has died ” + ”because of a #{reason.class}” end end
57. irb(main)> warsaw = Capital.spawn irb(main)> wroclaw = City.spawn irb(main)> wroclaw.link warsaw irb(main)> warsaw.decapitalize! RuntimeError: Over our dead bodies capital.rb:5:in ‘decapitalize’ #<Celluloid::Actor(Capital) dead> has died because of a RuntimeError => nil
58. Erlang ⇝ Ruby
59. Observation no. 4 Ideas from Erlang work great in Ruby
60. This slide is intentionally left blank
61. bondjoû halló aang aloha nyob zoo szia glid tánishi здравей salut привіт sawubona пр экии servus اًبحرم γεια coi բարև boozhoo прывітанне hola salam ни хо おはよう helo molo mandi watawieh žívjo halò saluton lab ora zdravo χαίρε mauri саламатсыздарбы םֹולָׁש кюнюгюз ашхы болсун sekoh talofa b ahoj cześć terve hai bonjou tere jambo bon kusheh manao ahoana bonġu mālō e lelei h sannu رصع ریخب msawa yáʼátʼééh alii bou ola уузыншэм yiem longx nyei uè dia dhui merhaba бзиа збаша ⴰⵣⵓⵍ ciao xin chào ສ сәлем sveiki hej mari mari sälü здраво sal
62. Człowiek człowiekowi wilkiem. A human is a wolf to a human.
63. Linguistic relativity Our mother tongue affects the way we think
64. e Power and Philosophy of Ruby Matz, 2003
65. Natural languages affect the way we think and express ourselves.
66. Beating the Averages Paul Graham, 2001
67. . . E . Blub . Assembler . Pascal . Foo
68. . . E . Blub . Foo . Foo#
69. Learn a new language every year. Andrew Hunt, David omas e Pragmatic Programmer: From Journeyman to Master
70. Observation no. 5 Polyglots have a wider perspective
71. Your post-conference checklist ☑ Download a different programming language ☑ Use it and find things you don’t get ☑ Try to understand ☑ See how it applies to Ruby ☑ Apply it to Ruby ☑ Send your findings to jan@stepien.cc
72. By relieving the brain of all unnecessary work, a good notation sets it free to concentrate on more advanced problems. Alfred North Whitehead An Introduction to Mathematics Henry Holt & Co, 1911
73. Embrace the static Cherish the functional Remain a Rubyist jan@stepien.cc @janstepien