This document summarizes Kang-min Liu's presentation on learning from Ruby. Some key points discussed include: - Ruby concepts like classes, self, and blocks that were inspired by Perl - Useful Ruby classes and features like ranges, lazy evaluation, and autoboxing - How concepts from Ruby like blocks and coroutines could be implemented in Perl - Examples of Ruby code and how similar functionality can be achieved in Perl - The DisasterTW website created during a Taiwan typhoon using Ruby on Rails hosted on Heroku

1. Learning from
Ruby
Kang-min Liu <gugod@gugod.org>
YAPC::Asia::2009

2. Gugod->meta
• • http://handlino.com/
Kang-min Liu
gugod
• http://gugod.org
• http://search.cpan.org/
~gugod/
• http://twitter.com/gugod
• gugod@gugod.org

3. Learning from
Ruby

4. Learning from
Ruby

5. Ruby is Lovely
(The programming language)

6. Perl 6 Logo

7. Language

8. rubyisms.pm
by Simon Cozens

9. rubyisms.pm
• Class
• new
• self
• super
• yield

11. Perl ~~ Ruby

12. Ruby

13. self

14. class Foo
def bar
self.baz
end
def self.bar
self.baz
end
end

15. class Foo
def bar
object
self.baz
end
def self.bar
self.baz
end
end

16. class Foo
def bar
object
self.baz
end
Class def self.bar
self.baz
end
end

17. class Foo
def bar
baz
end
def self.bar
baz
end
end

18. block syntax

19. def foo(arg1, arg2)
yield(a, b)
end
foo(arg1, arg2) do |block_arg1, block_arg2|
...
end

20. co-routine

21. callback

22. call me after you
done that.

23. div(id => "content") do
h1(id => "title") { "OHAI" }
p(class => "block") { "Cheeze?" }
end

24. app do
alert(42)
end

25. Good Built-in
Classes

26. Range

27. Lazy

28. irb> 1..2**100
=>
1..1267650600228229401496703205376
irb> (1..2**100).class
=> Range

29. (1..2**100).each do |i|
puts 42
break if i >= 5
end

30. autobox

31. no Semicolon

32. Rubyish.pm
It’s all sugar, honey.

33. Rubyish.pm
• Kernel, Object, Module, Class
• Array, Hash, String, TrueClass,
NilClass, Enumerable
• Syntax
• def, nil, true, false

34. class Foo {
}

35. def foo {
# $self;
}

36. def foo($arg1, $arg2) {
}

37. see also:
MooseX::Declare

38. my $array = Array[0..3];
if ($array->any { $_ > 2 }) {
...
}

39. # Rubyish::Array
$arr = Array[1..10];
# Rubyish::Hash
$hash = Hash{ a => 42, b => "stuff" };
# Rubyish::String
$str = String("FooBar");

40. ref:
Class::Builtin

41. boolean
• true – TrueClass
• false - FalseClass
• nli - NilClass

42. sub true() {
Rubyish::TrueClass->new
}

43. ref:
boolean.pm
and Acme::Boolean

44. Hash is lazy too

45. fib = Hash.new { |fib, k| fib[k] = fib[k-1] + fib[k-2] }
fib[0] = 0
fib[1] = 1
puts fib[10]
# => 55

46. Functional
programming
-ish

47. Memoize
sub fib {
my $n = shift;
return $n if $n < 2;
fib($n-1) + fib($n-2);
}
memoize('fib');

48. Lazy stuffs
• Scalar::Lazy
• Variable::Lazy
• Scalar::Defer
• Data::Thunk

49. Lazy stuffs
• Tie::Array::Lazy
• Tie::Array::Lazier
• Hash + Lazy = ?

50. Hash::Lazy

51. Hash::Lazy
my $fib = Hash {
my ($h, $k)= @_;
return $h->{$k-1} + $h->{$k-2}
};
$fib->{0} = 0;
$fib->{1} = 1;
say $fib->{10}; # 55

52. Hash::Lazy
• export “Hash” as the constructor
• Hash::Lazy::Tie

53. Learnt
• I hate doing tie
• Spiffy constructors can be good
read
• Hash
• Rubyish.pm: Array, Hash, String
• Class::Builtin: OO

54. PerlX::MethodCall
WithBlock
Still more syntax sugar

55. Schwartzian
Transform
Ruby
(0..10)
.map { |i| i * 13 }
.map { |i| i % 17 }
.sort { |a,b| a <=> b }

56. Schwartzian
Transform
Perl5
sort { $a <=> $b }
map { $_ % 17 }
map { $_ * 13 }
(0..10)

57. Schwartzian
Transform autobox
Perl5, with
[0..10]
->map(sub { $_ * 13 })
->map(sub { $_ % 17 })
->sort(sub { $a <=> $b })

58. Schwartzian
Transform
Perl5, extended!
[0..10]->map {
$_ * 13
}->map {
$_ % 17
}->sort {
my ($a,$b) = @_;
$a <=> $b
};

59. Schwartzian
Transform
Perl5, extended!
[0..10]
->map { $_ * 13 }
->map { $_ % 17 }
->sort { $_[0] <=> $_[1] }

60. PerlX ::
MethodCallWithBlo
ck

61. ref
• B::OPCheck
• lineseq, pushmark, const
• B::Hooks::EndOfScope
• Devel::Declare

62. ref
• opcode.pl, opcode.h
• B::Concise
• B::Deparse

63. PerlX

64. Community

65. Last month

66. Sh*t happened

67. Taiwan

68. Morakot

70. ☹

73. $WebSite.com

75. xdite

76. ☹

77. DisasterTW.com

78. DisasterTW.com
• Forum
• Initial Coding: 1 hour*woman.

80. 1 day later

82. DisasterTW.com
• Web 2.0 / Social-ish
• Multi-Function
• Mash-able

83. DisasterTW.com
✖
• Web 2.0 / Social-ish
• Multi-Function
• Mash-able

84. DisasterTW.com
• Online ASAP
• Robust (peak: 400k PV/day)
• Well-known

85. DisasterTW.com
• Rapid Prototyping
• Cloud Computing
• SEO / Social Network Friendly

86. DisasterTW.com
• Ruby on Rails
• Heroku + Panther CDN
• Good HTML / Plurk button

87. DisasterTW.com
• 6 heroku instances
• Thousands of tweets about
#morakot
• Total Cost: ~50 USD

89. People are
awesome

90. Tools are
awesome

91. Problem →

92. What if it was a
Jifty site?

93. @obra can haz
dancing

94. @obra can haz
dancing, naked

95. DisasterTW.com
• Rapid Prototyping
• Cloud Computing
• SEO / Social Network Friendly

96. DisasterTW.com
• Jifty
• Cloud Computing
• Good HTML / Plurk button

97. Heroku for Perl?

98. ∴

99. Ruby is Lovely

100. Ruby is a
respectful friend
of Perl

101. Ruby programmers
are respectful friends
of Perl programmers

102. Thanks for Listening