Lovely! It reminds me of some methods of generating images with genetic programming, e.g. Karl Sims, http://dahart.com, and http://picbreeder.org. The main difference being a stack-based representation versus a tree-based one. Some people do use stack-based genetic programming, so it would be fun to hook this up to one of those systems and evolve textures.
One nice feature in the above strand of research is that the output value, instead of being mapped to a greyscale, is mapped via a colour map to produce colour images.
One nice feature in the above strand of research is that the output value, instead of being mapped to a greyscale, is mapped via a colour map to produce colour images.