Maybe nobody is suprised that the book “Structure and Interpretation of Classic Mechanics” by Sussman & Wisdom contains code that you can put in any old Scheme/Lisp environment to actually represent mechanical equations.
Like this expression:
Turned into this code:
(define q (up (literal-function ’x) (literal-function ’y) (literal-function ’z))) (q ’t) ;; => (up (x t) (y t) (z t))
Imagine if it was interactive on the web!
It should not be a surprise because the book title is so similar to “The Wizard Book”, “Structure and Interpretation of Computer Programs”. Which is a very, very interesting read, both to get to know their didactics for hands-on “how to learn to program” course, and to see how you can actually express weird concepts in a functional language.
Both books are super fascinating, and both links here point to the MIT Press pages where you can read the books for free, online. That’s right: With copy & pasting of the code.