User guide What is Haml? This is the best Haml definition: Haml takes your gross, ugly templates and replaces them with veritable Haiku. Haml is the next step in generating views in your Rails (also in PHP) application. Haml is a refreshing take that is meant to free us from the shitty templating languages we have gotten used to. Haml is based on one primary principal. Markup should be beautiful.