{ config, pkgs, lib, ... }: with lib; let cfg = config.programs.custom.elm; in { options.programs.custom.elm.enable = mkEnableOption "enable elm stack"; config = mkIf cfg.enable { environment.systemPackages = with pkgs; [ elmPackages.elm elmPackages.elm-compiler elmPackages.elm-format elmPackages.elm-make elmPackages.elm-reactor elm-github-install ]; }; }