Mirah Talk for Boulder Ruby Group

2. Mirah

3. What’s Mirah?

4. It’s a small, fast, JVM language that uses Ruby syntax.

5. How’d it come about?

6. Charles Oliver Nutter, JRuby guy

7. Wanted to write Java code in Ruby

8. Wanted to write Java code in Ruby

9. Wanted to write Java code in a language as expressive as Ruby.

10. Expressive as Ruby?

11. http://www.ﬂickr.com/photos/caroslines/513429518/

12. Syntactic Sugar • Optional Arguments • Internal Iteration(each, map, etc) • Closures • Literals • String Interpretation

13. Mirah's got the sugar.

14. How Mirah Differs from Ruby

15. 1. It’s statically typed and compiled

16. Basically, No Runtime Object/Class Modiﬁcation

17. 2. It uses Java’s type system

18. It has slightly different semantics than Ruby's

19. e.g., Mirah has interfaces

20. So, what’s it look like?

21. Fibonacci Example

22. Ruby def fib(a) if a < 2 a else fib(a - 1) + fib(a - 2) end end

23. Mirah github.com/mirah/mirah/examples/ﬁb.mirah def fib(a:int):int if a < 2 a else fib(a - 1) + fib(a - 2) end end

24. See what I did there?

25. def fib(a:int):int

26. def fib(a:int):int

27. Ruby Syntax + Java Types - Runtime Modiﬁcation

28. Other Super Powers

29. Type Inference & Macros

30. Type Inference?

31. Java class Foo { private int bar; Foo() { bar = 1; } public int bar() { return bar; } }

33. Ruby class Foo def initialize @bar = 1 end def bar @bar end end

34. Mirah class Foo def initialize @bar = 1 end def bar @bar end end

35. @bar is inferred to be an Integer

36. Mirah class Foo def initialize @bar = 1 end def bar @bar end end

37. Java class Foo { private int bar; Foo() { bar = 1; } public int bar() { return bar; } }

38. Mirah Java // Generated from foo.mirah public class Foo extends java.lang.Object private int bar; public Foo() { this.bar = 1; } public int bar() { return this.bar; } }

39. Ruby Syntax + Java Types - Runtime Modiﬁcation + Type Inference

40. Macros

41. For Convenience & Awesomeness.

42. Used by the compiler

43. For example,

44. puts => System.out.println();

45. Macros: How each, map, ==, etc are implemented

46. Macro Basics

47. say you have code like: logger.debug( "this #{takes_too_much_time}" )

48. run takes_too_much_time in production?

49. No, it takes too much time.

50. Macros to the rescue

51. macro def debug debug_input quote do if logger.debugEnabled logger.debug `debug_input` end end end

56. debug( "this #{takes_too_much_time}" )

58. if logger.debugEnabled logger.debug( "this #takes_too_much_time}" ) end

59. debug( "this #{takes_too_much_time}" )

60. So, Macros are nifty

61. Ruby Syntax + Java Types - Runtime Modiﬁcation + Type Inference + Macros

62. Oh, there's another thing.

63. No Runtime Library

64. You can do this: $ mirahc -e "puts 'hello BRG'" $ java -classpath . DashE.class

65. No Runtime == Small compiled footprint

66. Small Footprint == good for mobile

67. For example, see Pindah

68. Ruby Syntax + Java Types - Runtime Modiﬁcation + Type Inference + Macros - Runtime Library

70. Get Started $ rvm jruby $ gem install mirah $ mirah -e "puts 'hello world'

71. Mirah projects to check out: • Dubious - Rails-like web framework for Google App Engine • Pindah - Android App framework

72. I'm Nick @baroquebobcat

73. I work at

74. We're Hiring. gnip.com/jobs

75. A couple links mirah.org github.com/mirah

76. Questions?

Mirah Talk for Boulder Ruby Group

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