Assignment 1 - Andrew Michaud.

You could do a gradient by making a rule/path that makes lines of constantly incrementing the hue by a small number, but that is limited in that it essentially needs to be along the sequence of color that hue uses (rainbow order?) or you would have to hard code it. 

The 'h' parameter when you call a rule _is_ an increment, but then you have to do you so-called loop recursively. I agree this is less than convenient to do well and control as wanted, but it is possible.