Make pkgsets accessible to service configurations.

configuration.nix

@@ -14,7 +14,7 @@ in {
     machineOpts
     ./config/default.nix
     ./pkgs/nixpkgs.nix
-    ./pkgs/pkgsets.nix
+    ./pkgs/systemPackages.nix
     ./services/containers.nix
     ./services/default.nix
   ];

machines/Behemoth/options.nix

@@ -25,7 +25,7 @@ with lib;
       "extra"
       "cpp"
       "haskell"
-      "mailutils"
+      "mail_utils"
       "python3"
       "rustpkgs"
       "xpkgs"

machines/Lilim/configuration.nix

@@ -10,7 +10,5 @@
 
   networking.dhcpcd.extraConfig = "noarp";
 
-  environment.systemPackages = with pkgs; [ xdiskusage ];
-
   system.stateVersion = "19.09";
 }

machines/Lilim/options.nix

@@ -25,7 +25,7 @@ with lib;
       "extra"
       "cpp"
       "haskell"
-      "mailutils"
+      "mail_utils"
       "python3"
       "rustpkgs"
       "xpkgs"

pkgs/nixpkgs.nix

@@ -1,14 +1,12 @@
-{ config, lib, ... }:
+{ config, lib, pkgs, ... }:
 
 {
   nixpkgs.config = {
     allowUnfree = true;
     mpv.vaapiSupport = (lib.elem "xserver" config.machine.services);
 
-    packageOverrides = pkgs: with pkgs; rec {
-      theme_flat-remix = callPackage ./flat-remix { };
-      theme_sddm_midnight = callPackage ./sddm_midnight { };
-      xdiskusage = callPackage ./xdiskusage { };
+    packageOverrides = {
+      pkgsets = import ./pkgsets.nix { inherit config lib pkgs; };
     };
   };
 }

pkgs/pkgsets.nix

@@ -1,13 +1,17 @@
-{ config, lib, pkgs, ... }:
+{ config, lib, pkgs }:
 
 with lib;
 
 let
   cfg = config.machine;
-  optPkgs = package: pkgstring: optionals (elem pkgstring cfg.pkgs) (toList package);
   gitpkgs = import /nixpkgs {};
   stablepkgs = import <nixos-stable> {};
 
+  callPackage = pkgs.callPackage;
+  theme_flat-remix = callPackage ./flat-remix { };
+  theme_sddm_midnight = callPackage ./sddm_midnight { };
+  xdiskusage = callPackage ./xdiskusage { };
+in {
   # Programms I'm likely to want on every machine and/or may execute as root
   base = with pkgs; [
     alsaUtils
@@ -236,7 +240,7 @@ let
 #    flask_testing
 #    flask_wtf
 #    flaskbabel
-  ] ++ optionals (elem "i3" cfg.desktop.wms) [ py3status pytz tzlocal ]);
+  ] ++ optionals (elem "i3" config.machine.desktop.wms) [ py3status pytz tzlocal ]);
 
   rustpkgs = with stablepkgs; [
     rustup
@@ -272,26 +276,4 @@ let
     xorg.xbacklight
     xdiskusage
   ];
-
-in {
-  environment.systemPackages =  base
-                            ++ (optPkgs dict "dict")
-                            ++ (optPkgs emacs "emacs")
-                            ++ (optPkgs extra "extra")
-                            ++ (optPkgs mail_utils "mailutils")
-                            ++ (optPkgs cpp "cpp")
-                            ++ (optPkgs haskell "haskell")
-                            ++ (optPkgs java "java")
-                            ++ (optPkgs python3 "python3")
-                            ++ (optPkgs rustpkgs "rustpkgs")
-                            ++ (optPkgs server "server")
-                            ++ (optPkgs uniProgs "uniProgs")
-                            ++ (optPkgs xpkgs "xpkgs");
-
-  services.emacs = mkIf (elem "emacs" cfg.pkgs) {
-    defaultEditor = true;
-    enable = true;
-    install = true;
-    package = emacs;
-  };
 }

pkgs/systemPackages.nix

@@ -0,0 +1,16 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+  cfg = config.machine;
+in {
+  environment.systemPackages = flatten (attrVals cfg.pkgs pkgs.pkgsets);
+
+  services.emacs = mkIf (elem "emacs" cfg.pkgs) {
+    defaultEditor = true;
+    enable = true;
+    install = true;
+    package = pkgs.pkgsets.emacs;
+  };
+}