Asynchronous Emacs Direnv Devshells

Figure 1: The Meeting of San Carlo Borromeo and San Filippo Neri ; emacs logo licensed under GPLv3 from Wikimedia On the bad side of town underneath the freeway overpass with a needle full of lisp is a wild-eyed man who likes to abuse emacs. That man is me. My eccentric technology tastes take on a particularly esoteric flavor when I start setting up language servers. In short: I sandbox every language (and language server) in its own Nix devshell. I have no system-wide python or node, for example. I pair these devshells with direnv so that my environments automatically appear when I’m inside of a project directory. I live inside of emacs and use the envrc package to make my environments appear in emacs in cases where they’re critical. For example, eglot needs its language servers in my $PATH. I keep my environments moderately up-to-date, so sometimes (not usually) my devshell can take a while to appear. Emacs is, as all elisp cult members know, singly-threaded. Out of the box, long…