To appreciate Lisp (or anything) is really to appreciate the underlying requirements (and that they are done).

Some people absorb requirements very well (and then appreciate them) if they force themselves to implement the requirements, which is fine. Even those people can't just confine their appreciation to that which they're able to implement, because then the scope of their appreciation will be rather small.

I really appreciate John Carmack's approach to determining shadow maps for a scene: the clever "cast a ray from a point on the surface to infinity and determine whether it intersects a shadow volume boundary an even or odd number of times" so then you know whether it's in the shadow volume (w.r.t a light source) or not. So we go backwards from a pixel on the screen, to some point on an object's surface. For each such point (consequently pixel) we can determine whether it's in shadow; and we can reduce that to a 2D shadow map in pixel space. Terrific, right? And about the shadow volumes, they are basically just conical shapes made using the 2D contour of the objects as seen from the POV of the light source, and capped at the end somewhere so they are finite. I'm not going to sit here and implement it all though. It's not that I couldn't find the time but that it's out of scope. I can play it out in my head though and see it working which is a good enough facsimile.