nix-repl> :lf github:nix-community/emacs-overlay
nix-repl> :u (lib.x86_64-linux.emacsPackagesFor packages.x86_64-linux.emacs-git).emacsWithPackages(epkgs: [ inputs.nixpkgs.legacyPackages.x86_64-linux.emacsPackages.mistty ])
M-x mistty
in emacs:
Symbol’s value as variable is void: mistty-mode-map
:p inputs.nixpkgs.legacyPackages.x86_64-linux.emacsPackages.mistty.recipe.drvAttrs
See szermatt/mistty#14 for more possible insight, i. e. this would be the precise nix way: