I've had 13 hour flights. Unbearable! By the time I got to my destination the first time, I had a severely thorough understanding of Lisp macros. There isn't m

I've had 13 hour flights. Unbearable! By the time I got to my destination the first time, I had a severely thorough understanding of Lisp macros. There isn't much else to do, other than look out the window at clouds and ocean, or darkness as the time of day dictates. So I use it to learn things I otherwise "don't have the time for" but genuinely am interested in.