[lr1970]

> Textadept[1] is also quite nice, and configured (but not written) in lua. It seems to work fine in MacOS, but I haven't used it extensively. [1] https://orbitalquark.github.io/textadept/

Straight from your link above:

> "... the editor consists of less than 2000 lines of C code and less than 4000 lines of Lua code."

So it is written in Lua and C (mostly for graphics widgets).