slim-rails provides Slim generators for Rails 3 and 4. It was based on haml-rails and it does basically the same: configures Slim as the template engine automatically for your rails app. To use it, add this line to your Gemfile:

gem "slim-rails"

And that's it.

From the version 0.2.0, there is no need to include gem "slim" in your Gemfile.

Every time you generate a controller or scaffold, you'll get Slim templates.