Better syntax for applying generators to slugs

[soulcutter]

I don't know quite what this will look like yet, but it's been on my mind that there has got to be a friendlier way to apply generators to slugs. Possibly a fluent interface (chaining calls rather than passing objects).

This issue is a placeholder to give this a bit more thought, even if nothing pans out. There. Now it's out of my brain and into a tracker.