Programming languages must be implemented in Java or C, everybody knows this. Sure, a prototype in Ruby, but that would be unusable. After all, Ruby is made for web development, right? Hard tasks, like implementing a compiler, have to happen in far more manly languages. But wait, the Rubinius compiler is written completely in Ruby, and it seems to get pretty decent performance, maybe we can use that. In this talk, we will explore the possibilities of using the Rubinius compiler tool chain to implement our own programming language targeting the Rubinius VM. We get all the hard work that went into Rubinius for free and above all, can do the heavy lifting in Ruby, everyone's favorite programming language. As an example we'll use Reak, a Smalltalk implementation running on Rubinius.

1. Smalltalk On
Rubinius
Konstantin Haase

10. Why implement
Smalltalk on Rubinius?

11. Why create a
programming language?

12. Why create?

13. "When you don't create things, you become
defined by your tastes rather than ability. Your
tastes only narrow and exclude people. So
create."
why the lucky stiff

14. Why a programming
language?

15. About programming languages:
"I don’t like any of them, and I don’t think any of
them are suitable for the real programming
problems of today, whether for systems or for
end-users"
Alan Kay

16. Problem Oriented
Programming Languages
Cairo (~120k SLOC in C) rewritten in less than
400 lines

17. Why Smalltalk?

18. Why Rubinius?

20. 1 + 1
1 + 1

21. this is it
this.is.it

22. GoGaRuCo rock: #hard
GoGaRuCo.rock :hard

23. doc convertFrom: #xml to: #yaml
doc.convert(:xml, :ruby)

24. doc convertFrom: #xml to: #yaml
doc.convert from: :xml, to: :ruby

25. [ 42 ]
proc { 42 }

26. anArray do: [ :each | each doSomething ]
an_array.each do |element|
element.do_something
end

27. Textmate version = 2
ifTrue: [ 'no way' ]
ifFalse: [ 'thought so' ]
if Textmate.version == 2
"no way"
else
"thought so"
end

28. Storage current
store: #foo;
store: #bar
storage = Storage.current
storage.store :foo
storage.store :bar

29. Smalltalk claims to look
like: 'English'.
Judge yourself. Does it.
Ruby.claims.to.look.
like "English"
Judge.yourself; Does.it?

30. Reak
github.com/rkh/Reak
Like Squeak but with R
File based (as opposed to image based)

32. The Rubinius Compiler
Pure Ruby
Modular and Flexible
lib/compiler

34. Parsing with KPeg
github.com/evanphx/kpeg

35. " from Reak.AST.Self "
grammar: g [ ^ g str: 'self' ]
# from Reak::AST::Return
def bootstrap_grammar(g)
g.seq "^", :sp, g.t(:expression)
end

36. Rubinius Bytecode

37. $ rbx compile -B -e 'puts "Hello World"'
0000: push_self
0001: push_literal "Hello World"
0003: allow_private
0004: send_stack :puts, 1

38. $ rbx compile -B -e 'puts "Hello World"'
0000: push_self
0001: push_literal "Hello World"
0003: allow_private
0004: send_stack :puts, 1

39. $ rbx compile -B -e 'puts "Hello World"'
0000: push_self
0001: push_literal "Hello World"
0003: allow_private
0004: send_stack :puts, 1

40. $ rbx compile -B -e 'puts "Hello World"'
0000: push_self
0001: push_literal "Hello World"
0003: allow_private
0004: send_stack :puts, 1

41. $ rbx compile -B -e 'puts "Hello World"'
0000: push_self
0001: push_literal "Hello World"
0003: allow_private
0004: send_stack :puts, 1

42. class Object
dynamic_method(:display) do |g|
g.push_self
g.push_local(0) # first argument
g.send(:puts, 1, true)
g.ret
end
end
display "Hello World"

43. Reusing the Rubinius
tool chain

45. class Reak::Compiler < Rubinius::Compiler
class Parser < Stage
stage :parser
next_stage Generator
end
end

46. class CustomNode < Reak::AST::Base
def self.bootstrap_grammar(g)
# grammar definition
end
def bytecode(g)
# bytecode definition
end
end

47. class ConstantAccess < Rubinius::AST::ConstantAccess
include Reak::AST::Node
Reak::AST::Primary.push self
def self.bootstrap_grammar(g)
g.t /[A-Z][a-zA-Z0-9_]*/
end
# no bytecode definition necessary
end

48. Rubinius.AST.TrueLiteral subclass: #TrueLiteral [
Reak.AST.Primary push: self.
self include: Reak.AST.Node.
self class >> grammar: g [
^ g str: 'true'
].
]

49. " Remember cascades? "
g
pushSelf;
pushLocal: 0;
send: #puts args: 1 private: true;
ret.

50. Reak.AST.Base subclass: #Cascade [
Reak.AST.Expression push: self.
bytecode: g [
g pushSelf.
cascadedSends do:
[:send |
g dup.
send bytecode: g.
g pop ].
lastSend bytecode: g.
]
]

51. Thanks!
github.com / rkh / presentations