I got the following output from pry
when trying out the example from http://rubini.us/doc/en/systems/concurrency/ with Rubinius 2.2.9:
2.1.0 (main):0 > RUBY_VERSION
=> "2.1.0"
2.1.0 (main):0 > RUBY_PATCHLEVEL
=> 0
2.1.0 (main):0 > RUBY_PLATFORM
=> "x86_64-darwin13.2.0"
2.1.0 (main):0 > RUBY_ENGINE
=> "rbx"
2.1.0 (main):0 > require 'actor'
LoadError: no such file to load -- actor
from kernel/common/code_loader.rb:441:in `load_error'
Is the documentation outdated?