[chriseppstein]

There's no "gradual creeping" or "ad-hoc" language features being added "on the fly". We spend a lot of time thinking about what features are included in Sass and most feature concepts do not get added.

Feel free to write your CSS in ruby, it would take less than a week to whip up a DSL for CSS, but good luck trying to get a designer to use it ;)

[djacobs]

Don't get me wrong, I'm a huge fan of SASS and Compass and think variables have been implemented well. But retroactively adding functions feels ad-hoc, even if great care was taken when adding the feature. I feel that designers might be more likely to write Ruby methods than these style functions (though of course I don't have data to back that up).