I agree: he loves to "roll your own" a lot. Re: minimal dependencies - the codebase has a software FP implementation including printing and parsing, and some home-rolled math routines for trigonometric and other transcendental functions.

Honestly, it's a reminder that, for the time it takes, it's incredibly fun to build from scratch and understand through-and-through your own system.

Although you have to take detours from, say, writing a bytecode VM, to writing FP printing and parsing routines...