You need to define the identity element (identity function), some absorbing elements (like not) and you’ll be all set :)

I gave a presentation using slideshow. The archivist wants a PDF. PDF generation stopped after the 5th slide. I saw an error "slide program attempted to execute external code: $<path:C:\texlive\2019\bin\win32\latex.exe>. I have some equations in my slides. Is there an easy way to have all the sides render to PDF?

Use the --trust flag for slideshow to allow subprocesses.

Aw, I was about to suggest to take screenshots :grin:

Thank you @mflatt! Of course I should have guessed it would be so simple and that you solved this long ago. That did the trick!

scribble / latex: I want to write @equation["A" "B"] and get \begin{equation}\label{A}B\end{equation}

Is there a way to do this “directly” in scribble? I tried nested and compound-paragraph , but both put newlines between their blocks and that seems to give a latex error (missing $ inserted)

For now, I’m making a 'multiarg element

I’m not sure if the decoding step of nested is confusing things, but maybe you should directly construct a nested-flow to avoid it. Also, it looks like you want a single block in the nested flow, not a list with separate blocks for A and B.

Racket is a good starting point for learning functional programming?

Sure. Or even programming in general. See https://htdp.org/2020-5-6/Book/index.html

Thanks!