nixos/pkgsets/emacs/yaml-mode.nix

{
  config,
  lib,
  pkgs,
  ...
}:
with lib;
  mkIf (elem "emacs::yaml-mode" config.machine.pkgs) {
    programs.emacs.init.usePackage = {
      yaml-mode = {
        enable = true;
      };
    };
  }