MacRuby is a new implementation of the Ruby programming language powered by LLVM and built on top of CoreFoundation. It provides a fast and beautiful way for Cocoa developers to use Ruby while having full access to and integration with the Cocoa frameworks. While still in development, MacRuby aims to be a robust alternative to Objective-C that addresses limitations like code reuse and safety while maintaining compatibility.

1. Why MacRuby Matters
Patrick Thomson
C4[3]
September 2009

3. Edsger Dijkstra

4. “Go To Statement Considered Harmful”

5. Dijkstraʼs Algorithm

6. “The effective exploitation of the
powers of abstraction must be
regarded as one of the most vital
activities of a computer
programmer.”

7. Objective-C

8. insufficiently powerful abstraction

9. What does Objective-C lack?

10. 1. code reuse

11. inheritance alone
is not enough

12. singletons

13. inheritance

14. In Objective-C:
1. create a static, shared instance
2. initialize once and only once
3. add an sharedInstance accessor method
…for every singleton class.
Tedious.

15. tedium sucks

16. mixins

17. units of behavior;
mix-in common functionality
across unrelated classes

18. With mixins:
class Example
include Singleton
# your methods here
end

19. foo = Example.instance

20. not a new idea

21. Symbolics Lisp

22. 1980

23. 1. code reuse
2. safety

24. C is powerful.

25. C is powerful. (At the price of safety.)

26. We see Cʼs unsafeness throughout Objective-C.

27. raw pointers: bad news.

28. easily-confusable garbage collection

29. exceptions

30. creation, @try, and @throw are all expensive

31. Cocoa isnʼt exception-safe.

32. mishmash of NSError**,
NSException, and error codes

33. 1. code reuse
2. safety
3. syntactic abstraction

34. [NSArray arrayWithObjects: @"a", @"b", @"c", nil];
vs.
["a", "b", "c"]

35. [NSDictionary dictionaryWithObjectsAndKeys:
@"Chicago", @"location", @"C4", @"event", nil];
vs.
{"location" => "Chicago", "event" => "C4"}

36. [foo compare:bar] == NSComparisonResultAscending
vs.
foo < bar

37. I want a language that lets
Cocoa shine.

38. MacRuby.

39. new Ruby implementation

40. +
powered by LLVM

41. + +
on top of CoreFoundation

42. irb(main):001:0> "c4".class
=> NSMutableString
irb(main):002:0> [1, 2, 3].class
=> NSMutableArray
irb(main):003:0> {:tollfree => "bridging"}.class
=> NSMutableDictionary
irb(main):004:0> "/usr/local/bin".pathComponents
=> ["/", "usr", "local", "bin"]
Ruby objects Cocoa objects

43. irb(main):001:0> 3000.class
=> Fixnum
irb(main):002:0> 3000.is_a? NSNumber
=> true
irb(main):003:0> 3000.is_a? NSObject
=> true
irb(main):003:0> 3000.class.is_a? NSObject
=> true
Everything is an NSObject

45. Laurent Sansonetti
Vincent Isambart
Rich Kilmer
Eloy Duran
Ben Stiglitz
Matt Aimonetti

46. MacRuby isnʼt…

47. a bridge

48. MacRuby != RubyCocoa

49. a toy

50. provides real solutions to
real-world problems

51. example: threading

52. Global Interpreter Locks

53. only one system thread can touch
the interpreter at any given time

54. prevents true multithreading

55. MacRuby has no GIL!

56. So why should you, as Cocoa
developers, use MacRuby?

57. itʼs fast

58. historically slow

59. fib(40)

60. static int fib(int n)
{
if (n < 3) {
return 1;
} else {
return fib(n - 1) + fib(n - 2);
}
}

61. @implementation Fib
- (int)fib:(int)n
{
if (n < 3) {
return 1;
} else {
return [self fib:n - 1] + [self fib:n - 2];
}
}
@end

62. C Objective-C
4
3
execution time (s)
2
1
0
fib(40)

63. def fib(n)
if n < 3
1
else
fib(n-1) + fib(n-2)
end
end

64. C MacRuby Objective-C
4
3
execution time (s)
2
1
0
fib(40)

65. Faster than Objective-C‽

66. macruby --compile

67. first ahead-of-time compiler
for Ruby

68. itʼs beautiful

69. Objective-C:
[obj setValue:val forKey:key]

70. Bridges:
obj.setValue_forKey(val, key)
READABILITY FAIL

71. no_underscores_plz_k_thx

72. MacRuby:
obj.setValue(val, forKey:key)

73. HotCocoa

74. mapping Cocoa to idiomatic Ruby

75. [[NSImage alloc] initWithContentsOfFile:path];
becomes
image(:file => path)

76. [[NSGradient alloc]
initWithStartingColor: [NSColor greyColor]
endingColor: [NSColor blueColor]];
becomes
gradient(:start => color(:name => "grey"),
:end => color(:name => "blue"))

77. a real, robust macro system

78. itʼs conceptually sound

79. single inheritance
open classes
message-based object model
dynamically typed
garbage-collected

80. Objective-C is C with the Smalltalk
object model attached.
Ruby is Smalltalk with C syntax.

81. itʼs fully integrated with the
Cocoa toolchain

82. Yeah, We Got That

83. itʼs 100% compatible with every
Cocoa framework

84. BridgeSupport lets you call any
C-based API from MacRuby

85. CFStringGetLength("hello C4")
=> 8

86. queue = Dispatch::Queue.concurrent
queue.dispatch do
puts "Asynchronous dispatch FTW!"
end

88. it provides features that
Objective-C lacks

89. regular expressions,
tail-call optimization,
namespaces,
mixins,
operator overloading,
runtime evaluation…

90. What do you lose when going
from Objective-C to MacRuby?

91. static typing

92. JVM : Scala Cocoa : ?

93. Where are we now?

94. almost 0.5

95. SVN trunk is stable
(macruby.org)

96. nightly builds for 10.6 at
macruby.icoretech.org

97. What does the future hold?

98. Last summer I had an internship at Apple.
My views here, however, represent that of an open-source contributor,
and not an Apple employee. Any speculations on the future of MacRuby
are entirely mine and are in no way representative of any plans, attitudes,
or future directions that Apple may take. This presentation is neither
sponsored nor endorsed by Apple.
Apple: please donʼt sue me.

99. performance improvements

100. compatibility

102. not yet

104. Possible? Yes.
Certain? No

105. ahead-of-time compiler

106. MacRuby → x86/ARM machine code

107. full mode: packed with interpreter

108. restricted mode:
no eval(), no interpreter

109. compliant with Appleʼs restrictions
on interpreters in iPhone apps

110. we need garbage collection on
the iPhone

111. Stay Informed
@lrz
@importantshock
@benstiglitz
@MacRuby @vincentisambart
@mattaimonetti
@alloy