SaitoWu

def call_block
  puts "before call"
  yield
  yield
  puts "after call"
end

call_block{ puts "call" } #before call\ncall\ncall\nafter call

SaitoWu

#clone repl from github or download form http://neugierig.org/software/c-repl/ 

git clone https://github.com/martine/c-repl.git c-repl

#install dependencies

sudo apt-get install ghc6 gccxml libghc6-parsec-dev libghc6-mtl-dev \
                       libghc6-hunit-dev

sudo apt-get install gdb libexpat1-dev c2hs libreadline-dev

SaitoWu

#0> non-block call

Thread.new do
  blahbla...
end

#1> 4 simple ways to call shell or cmd

`ps aux`

SaitoWu

require 'open-uri'

img_url = "http://fffffffffffffffffffffffuuuuuuuuuuuuuuuuuuuuuu.com/big.jpg?im="

(1..1044).each do |x|
  n = '%.4d' % x + ".jpg"
  open(n, "wb").write(open(img_url+n).read)
end