1. Metaprogramming in Ruby ( II )
Thinking in Lisp in Ruby in Lisp in …
http://jon.is.emotionull.com

2. Creating a language
 Parsers from scratch
 Bison/yacc/lex
 Metaprogramming FTW!

3. Bow to the masters
 Lisp
 Scheme
 Forth
 Smalltalk

4. Thinking again the problem
 Code as data
 Self modifying code
 Dynamic adding/removing classes/functions
 Describe the problem, don't solve it!

5. Metaprogramming in the wild
 Web frameworks (Ruby On Rails)
 A.I
 DSL
 Configuration files
 ...

6. But, hooooow???
 Function pointers (C,C++)
 Open classes (Ruby)
 Metaclasses (Python)
 Lists (Lisp/Scheme/Clojure)

7. Tools of the trade for Ruby
 Operators Overriding
 OpenClasses
 method_missing
 Blocks and eval
 Lambda

8. Speed penalty – Not always
 Premature optimization
 Fast and smart VM (JVM)
 Bottleneck is somewhere else (DB)
 You are not smart enough. Deal with it!

9. Cuby
 Implemented in ~ 10 minutes
 Looks like C
 Feels like C
 FULLY extensible
 Trivial to add new libraries
 You can use available Ruby libs
 VM ~ 25 lines!

10. C in Ruby
 Example
// this is a test (example.cb)
include ”stdio”
main {
printf ”Hello Mr. %s !”, ”Jon”
}

11. C in Ruby : Functions
 Example
include ”stdio”
plea_for_merci_to name {
shout ”Please don't kill me” + name + ”!”
}
main {
plea_for_merci_to ”Jon”
}

12. Real usage
Prediction Modelling

13. Prediction Modelling
 Lots of data (sometimes more than 60GB)
 Long live C, Fortran, Lisp
 Do you know OpenMP? If not, find another job
 Speed, speed, speed

14. Predictions in Ruby?
 RubyVM is not very robust (think BIG > 10GB)
 Ruby is slow
 Ruby threading is difficult and bad
 Ruby does not SCALE!

15. You are right!
Thanks for watching!

16. But ruby is slooooow
 1.9 is waaay better than 1.8
 Jruby is the King of the Hill
 The bottleneck is not really here (hint: DB)

17. But ruby cannot scale!
 Threading in RubyVM is bad
 Fibers are way better
 I love Jruby

18. Learn from the best: OpenMP
 Standard for parallel processing
 Easy to use
 Very mature library

19. OpenMP example
 Example
#pragma omp parallel for
for (i = 0; i < arraySize; i++){
....
y[i] = sin( exp( cos( ­ exp( sin(x[i]) ) ) ) );
....
}

20. Can we do this in Ruby?
 Example
for j in 1..30
puts "Hello from iteration " + j.to_s
for i in 0..700000
c += a[i] * b[­i]
end
puts "I have just finished!"
end

21. In Cuby we trust
 Example
for j in 1..30
puts "Hello from iteration " + j.to_s
parallel {
for i in 0..700000
c += a[i] * b[­i]
end
puts "I have just finished!"
}
end

22.
Thank for watching! Questions?
Cuby available at:
http://github.com/jonromero/Cuby
http://jon.is.emotionull.com
jon@emotionull.com