Indentation
HAML uses indentation to express nesting. A line that's indented further than the previous line becomes a child of that line; a line at the same indent is a sibling; a line at a shallower indent closes one or more parents.
Two-space indent
Template::HAML currently expects two-space indentation:
| %section.container
%h1 Title
%ul
%li Foo
%li Bar
|
| <section class='container'>
<h1>Title</h1>
<ul>
<li>Foo</li>
<li>Bar</li>
</ul>
</section>
|
Inconsistent indentation is rejected
An odd-spaced indent is rejected with X::IllegalIndent: