By Blaine Cook.

http://romeda.org/blog/2007/04/mapreduce-in-36-lines-of-ruby.html

If you want to add `dinject` (reduce) please do:
http://github.com/defunkt/mapreducerb

In your shell:
$ sudo gem install RingyDingy
$ sudo gem install ruby2ruby
$ ring_server &
$ ruby mapreduce_runner.rb &
$ ruby mapreduce_runner.rb &

In IRB:
>> require 'mapreduce_enumerable'
>> (1..100).to_a.dmap { |v| v * 2 }