Interestingly, I am tired of most projects declaring the language in which they were written upfront, especially when they are a copy of something else, "but written in ${language}!" - however, I am interested in the language a text editor is written in. Or, rather, the language it's extensible in.

I'm a long-time Emacs user, but have been growing increasingly tired of it. Whichever incarnation of Emacs I turn to, it just seems old-fashioned and outdated. And yet, whenever I try another editor, I end up coming back to Emacs. And one of the reasons is often the language (or ability at all) with which to extend it.