Download
Standard Gem
Most people will just want the standard stable Haml gem. To install this:
gem install haml
Pre-Release Gem
To get the latest and greatest Haml goodness, you can install the prerelease gem:
gem install haml --pre
You can see what versions of Haml are available on its page on RubyGems.
Git
You can access Haml's source code from its GitHub repository.