Yes, Joy is amazing. I have been working through the Advent of Code puzzles with it and the code keeps coming out error-free. It delivers on Backus' idea of algebra of programs (aka "Functional Programming") in a direct and entertaining way. It also seems amenable to efficient compilation.

I'm pretty sure Joy is a kind of "silver bullet" for programming, in the sense that, as "software is eating the world", Joy will eat software.

I have some Jupyter Notebooks here (also in HTML and md formats; md is good for looking at the 'books in situ on github): https://github.com/calroc/joypy/tree/master/docs