Demo of a C++23 TeX engine

What if we rewrote TeX82 today, thinking about the realities of modern typesetting? This is a demo of a C++ hobby project I've been working on. It builds a new TeX engine, shifting the boundary of what parts of TeX live in the macro layer vs at the engine level. This allows it to natively use OpenType fonts, build an intermediate representation of the page that is decoupled from the typesetting, and some other fun things. Because of this architecture, the engine can compile documents in parallel, output to PDF/UA-2 for accessibility, and generate absolute-positioned HTML/CSS directly from TeX source. (Typing and talking at the same time is hard -- please forgive some of the inaccurate things that mysteriously get said! Also, the trip test failure at the end of the video was in the first-phase log file, and was caused by an extra newline character I was adding whenever there was a "No pages of output." message...... all fixed up now). Let me know what you think in the comments! I have yet to make the git repo public (I still have to clean up some licensing / deal with a bunch of files that I threw into the repo for convenience while I developed it), but in the meantime if you want to know more about the architecture or how a specific feature works, ask in the comments! I'd love to make more videos breaking down how it's built under the hood. 00:00 - Introduction 01:51 - Compiling plain TeX 03:07 - Parallel compilation 04:18 - Generating accessible PDFs 06:33 - Intermediate representation of pages 07:22 - Setting up presentation slides 08:22 - Compiling TeX to HTML/CSS 12:00 - Pros and cons 12:55 - Ctest and Knuth's Trip Test