How can I use haml instead of HTML?

Is there a way to use haml preprocessor with a ionic project?

Yeah, by compiling Haml to HTML. You gotta install Haml, e.g. gem install haml or apt-get install ruby-haml, then refer to the manual and an example

I use Haml for Rails. I want to know if is there any ionic starter kit with haml so using “ionic serve” I have the haml autocompile (and maybe also coffee autocompile).

Or maybe a good suggestion for a Gulp plugin!

I’ve been using this Gruntfile for my ionic projects (it can be improved, but it’s a good starting point). Basically, it will listen for changes in any of your coffee/scss/haml files and compile to the corresponding js/css/html format. It will also apply ngAnnotate to your Angular files.