icomplete-vertical VS prism.el

You can display icomplete/fido vertically if you like that better with (setq icomplete-separator "\n") or with https://github.com/oantolin/icomplete-vertical

I don't use icomplete nor vertico most of the time, but I am very familiar with them. I've tried lots of completion UIs: default completion, ido (with ido-completing-read to get it everywhere), icomplete, vertico, selectrum, helm, ivy; and I've written several myself: icomplete-vertical, live-completions, grille, embark-collections-completions.

Helm commands only work in Helm. Ivy and Counsel commands only work in Ivy. Consult commands work in Selectrum, Vertico, Icomplete Vertical, and maybe some other interfaces. That's all I meant. Of course, that only matters if you don't wish to use Helm or Ivy.

Consult supports asynchronous candidate sources now! This allows to implement grep and find commands which update the candidate lists while you type. Consult is made to work well with the default completion system, Selectrum and Icomplete-vertical.

Heh, seriously, though, it's not necessary to use a rainbow of colors. You can use any number of colors and rotate through them. For example, this uses just 3 colors, gradually desaturating them as the depth increases. Since each color is easily distinguished from the other 2, it makes code very readable: https://github.com/alphapapa/prism.el/raw/master/images/parens-0.5.png

If you can use tree-sitter, that's obviously a good choice. Alternatively, you can see how I implemented https://github.com/alphapapa/prism.el, which isn't regexp-based, using Emacs's built-in syntax parsing instead.

I did some experimenting with supporting XML directly in https://github.com/alphapapa/prism.el/issues/16. It seems that it's not easily done with existing Emacs SGML-related functions, but I'm guessing that tree-sitter will help a lot in Emacs 29.

It's not exactly what you asked for, but you may also find this useful: https://github.com/alphapapa/prism.el It can highlight parens distinctly too.

As examples, I can recommend code in https://github.com/alphapapa/highlight-function-calls (simple) and https://github.com/alphapapa/prism.el (more complex).

There is also the package prism.el.

The best advice I can offer is to carefully and repeatedly study the Elisp manual section on font-lock, and to model on the source code of a similar project. The most I've done with it is in https://github.com/alphapapa/prism.el

There is one for emacs. Could be good inspo if someone wanted to make a VSCode version.

https://github.com/alphapapa/prism.el

You might be interested in https://github.com/alphapapa/prism.el