coffee-script-pure is a CoffeeScript compiler running in pure Ruby. It adopts the same protocol as ruby-coffee-script:
require "coffee-script-pure" CoffeeScript.compile "console.log 'hello world'", bare: true # => "\nconsole.log('hello world');\n"
A compiled and deflated copy of the CoffeeScript 1.2.0 compiler is bundled with coffee-script-pure.
gem install coffee-script-pure