About
Mostly Scala 3, with some other languages scattered in.
I have installed cats-core as well, and many solutions use it. I probably won't declare when I do use it, so if you can't find it in std it's probably in cats core.
I also have a common library that includes some helpers for 2d points, int math, directions, and grids. Depending on when a page was written I may explicitly rewrite a common library class/function and include it. Other pages I may just state "this is from my common library." You can view the general library code here.