HAML (HTML Abstraction Markup Language) is a lightweight markup language. It’s designed to address many of the flaws in traditional templating engines, as well as making markup as elegant as it can be. Haml functions as a replacement for inline page templating systems such as PHP, RHTML, and ASP. However, Haml avoids the need for explicitly coding XHTML into the template, because it is itself a description of the XHTML, with some code to generate dynamic content.
Like Markdown, Haml makes writing HTML much easier. With Haml, almost every developer, whether they would ever consent to use it or not, should immediately see the intense timesaving benefits that it brings to the table. Now every framework has ability to convert HAML to normal HTML like documents including Ruby, Python or even PHP.
Sometimes a view with bunch of logic inside takes many lines of code and you could easily forget to close HTML tags or something. HAML will close tags for you!
HAML markup language is really easy to learn. See some examples, try them online or maybe add HAML converter on the fly in your product.