[enriquto]

If you are more mathematically inclined, there's also "Functional Differential Geometry" by the same authors, and in the same spirit, but much shorter. The goal of the book is essentially to write the Euler-Lagrange equations in lisp, which is a breathtakingly beautiful thing.

[mseri]

Which is also especially beautiful, and open access as well: https://mitpress.mit.edu/books/functional-differential-geome...