Imitation Is NOT The Highest Form of Usability.

I really appreciate Slim view templates. What I don’t appreciate is Haml-style shorthand for things like CSS class names.

Haml (and Slim) allow you to code

<span class="foo bar">blah blah</span>

as

span.foo.bar
  blah blah

That works just fine, until you have class names (as in Bootstrap or UIKit with dashes (hyphens) in the class names.

If you want to code

<div class="col-md-8">
  <!== markup... -->
</div>

the naive Haml-influenced stylist might write

.col-md-8
  / ...
/ ...more markup...

which won’t work. Ruby comes along, interpreting the Haml/Slim DSL, and looks for variables named col and md to build the expression col - md - 8, and barfs when it can’t.

The fix is to write the HTML without the angle brackets:

div class="col-md-8"
  / ...
/ ...more markup...

You Have Been Warned.