Some of the examples are mathematical in nature. For instance, there is about twelve pages in chapter 6 that concerns using an infinite list object to represent a sequence of increasingly accurate approximations to the solution of a certain financial problem. People who have studied calculus will immediately understand the ideas here; people who haven't might understand them anyway, and even if you don't you can always skip those examples; most of them have nothing in particular to do with math.

My own tendency is to write a lot of math stuff, because I find it very interesting, but while I was writing HOP I tried really hard to get rid of the mathematics, because I knew that a lot of people don't like it.