I just ran across this reddit post about Ultyas, a utility to convert UltiSnips to YASnippet format. I was about to move on but UltiSnips stirred a distant memory so I searched Irreal and found a couple of posts that talked about it. The TL;DR is that it’s a Vim package that serves the same purpose as Emacs’ YASnippet.
The reason I wrote about it was Gilles Castel’s astounding post in which he describes taking lecture notes live in the classroom using LaTeX. His secret sauce was a series of UltiSnips snippets that expanded into the appropriate LaTeX. At the time I speculated on using his system with Emacs and YASnippet, perhaps with AUCTeX or Org.
Some of Castel’s snippets were complicated and used regular expressions as the key, which YASnippet didn’t support so a 1-to-1 translation wasn’t possible. Still, various Emacs users—Karthink in particular [1, 2]—were able to do the same thing.
If you’re a student in Mathematics or one of the hard sciences or even a professional who has to write a lot of mathematics, being able to get it into your computer as quickly as Castel or Karthink do is a real win. If you’re interested in trying this yourself and you’re an Emacs user you might want to convert Castel’s snippets to YASnippet. If so, you may find the Ultyas utility useful.