This is a conceptual specification for what could/would/should be the preprocessor to end all preprocessors. Unfortunately, it is just that - a specification. I had made quite a few attempts to create a CSS preprocessor, but I am far too inexperienced with advanced programming to succeed at this task. I got as far as the scanner and half of a half-working tokenizer before proceeding to pull my hair out. So I gave up, and decided just to list the proposed features here for reference. Perhaps these will make their way into existing pre-processors, or even inspire the birth of a new one.
Pretty much everything the 3 leading pre-processors offer in terms of: