> I've been using LaTeX for over ten years and I still wouldn't say that I "know" TeX in any meaningful way. I was not only productive but proficient in Typst in a day or two.

That's an interesting insight. Do you have an idea why this is? Do you have a CS background?

Isn't that everyone's experience? TeX is a nightmare. It predates all standards for sensible software.

That's also been my own personal experience, and I have a CS background and have written several papers and a PhD thesis in LaTeX. I have done many detailed figures in TikZ and done countless presentations using Beamer.

I have no idea how to implement anything in TeX on my own besides rudimentary macros. I did once try to implement a simple typesetting package for typesetting some particularly gnarly natural deduction trees, and I thought it worked fine for a few examples, but then it broke down in ways that was completely non-obvious to me.

The computational model of TeX is really, really opaque to me.

Yep, I'm a CS researcher in a top-3 department. (Hate to be all credentialist like that, but I'm guessing it does mean something to this audience.)

I think a lot of the reason is that, ok, LaTeX is extremely complicated. We all know this. Its partisans tend to believe that this is because typesetting is a hard problem. Typesetting is a hard problem! We know this, too. But I think that a substantial fraction of the complexity of LaTeX is accidental complexity stemming, ultimately, from the inherently loosey-goosey nature of the system.

See, there is no real abstraction in TeX. There are no real mechanisms for encapsulation/information hiding/whatever. It's all just characters that eat characters and turn into other characters. Anything can do anything. Anything can be anything. As a result, the whole "theory" of what a TeX program "is" (like in the sense that Peter Naur used that word?) is conventional.

This means that even to reuse other people's code, you have to imbibe decades of convention that's maybe semi-documented, maybe folkloric, or maybe perfectly sound but requires you to read a 230-page manual. I can only speak for myself, but for me, it's no way to live.

Now, again, TeX-lovers tend to claim that its high degree of loosey-gooseyness is necessary, that it's what makes TeX "powerful." I don't know, that sounds to me like the same old "you can't handle writing assembly" story. Sure I can. I'd just rather not if I can help it.

Maybe it's the PL person in me.

From experience, you don’t need to not have a CS background to find TeX/LaTeX difficult or obscure to customize or extend.

Here’s a challenge to try (I hacked together something similar that only works in specific cases): write an environment where you get N columns in portrait page mode, with a vertical ruler, say, 12pt to the left of each column; respecting different paper sizes.

The amount of \makeatother, and what does that even mean??, will blow your mind

I used to use LaTeX pretty frequently and although I was reasonably productive I also never felt that I "knew" it. It was a whole lot of googling "how to do x in latex" and pasting in something that was too arcane for me to remember for next time (and/or copy pasting from my own prior documents)

In all honesty, I only ever did it to achieve the "LaTeX look". These days I write in markdown or (gasp) wysiwyg editors like google docs.