How to highlight specific key words that start with a specil character

Im trying to wtite a major mode for emacs. There are some words like(!str, !float...) that I want them highlighted. How do I do it? For now, I am highlighting each part(! and the keyword) separatelly but that aint an elegant solution Basically Im asking for the regexp or how to make regexp-opt to do it for me.

I sometimes find rx helpful for figuring out the syntax: (require 'rx) (rx (? ?!) ;; Optional ! character (or "float" ;; One of "float" or "str" "str")) If you eval that you get `"!?\\(?:float\\|str\\)"`. You can also just use it directly when defining things: (defvar my-keyword-regexp (rx (? ?!) (or "float" "str")))