install_package "yaml-0.1.4" "http://pyyaml.org/download/libyaml/yaml-0.1.4.tar.gz#36c852831d02cf90508c29852361d01b" --if needs_yaml
install_git "ruby-1.9.3-dev" "https://github.com/ruby/ruby.git" "ruby_1_9_3" autoconf standard