nixos/xmonad: move to haskell-ng and make a wrapper

nixos/modules/services/x11/window-managers/xmonad.nix

@@ -3,11 +3,12 @@
 let
   inherit (lib) mkOption mkIf optionals literalExample;
   cfg = config.services.xserver.windowManager.xmonad;
-  xmonadEnv = cfg.haskellPackages.ghcWithPackages(self: [
-    self.xmonad
-  ] ++ optionals cfg.enableContribAndExtras [ self.xmonadContrib self.xmonadExtras]
-    ++ optionals (cfg.extraPackages != null) (cfg.extraPackages self));
-  xmessage = pkgs.xlibs.xmessage;
+  xmonad = pkgs.xmonad-with-packages.override {
+    ghcWithPackages = cfg.haskellPackages.ghcWithPackages;
+    packages = self: cfg.extraPackages self ++
+                     optionals cfg.enableContribAndExtras
+                     [ self.xmonad-contrib self.xmonad-extras ];
+  };
 in
 {
   options = {
@@ -19,9 +20,9 @@ in
       };
 
       haskellPackages = mkOption {
-        default = pkgs.haskellPackages;
-        defaultText = "pkgs.haskellPackages";
-        example = literalExample "pkgs.haskellPackages_ghc701";
+        default = pkgs.haskellngPackages;
+        defaultText = "pkgs.haskellngPackages";
+        example = literalExample "pkgs.haskell-ng.packages.ghc784";
         description = ''
           haskellPackages used to build Xmonad and other packages.
           This can be used to change the GHC version used to build
@@ -31,17 +32,17 @@ in
       };
 
       extraPackages = mkOption {
-        default = null;
+        default = self: [];
         example = literalExample ''
           haskellPackages: [
-            haskellPackages.xmonadContrib
-            haskellPackages.monadLogger
+            haskellPackages.xmonad-contrib
+            haskellPackages.monad-logger
           ]
         '';
         description = ''
           Extra packages available to ghc when rebuilding Xmonad. The
           value must be a function which receives the attrset defined
-          in <varname>haskellpackages</varname> as the sole argument.
+          in <varname>haskellPackages</varname> as the sole argument.
         '';
       };
 
@@ -58,12 +59,12 @@ in
       session = [{
         name = "xmonad";
         start = ''
-          XMONAD_GHC=${xmonadEnv}/bin/ghc XMONAD_XMESSAGE=${xmessage}/bin/xmessage xmonad &
+          ${xmonad}/bin/xmonad &
           waitPID=$!
         '';
       }];
     };
 
-    environment.systemPackages = [ cfg.haskellPackages.xmonad ];
+    environment.systemPackages = [ xmonad ];
   };
 }

pkgs/applications/window-managers/xmonad/default.nix

@@ -18,7 +18,7 @@ cabal.mkDerivation (self: {
   '';
   patches = [
     # Patch to make xmonad use XMONAD_{GHC,XMESSAGE} (if available).
-    ./xmonad_ghc_var_0.11.patch
+    ../../../development/haskell-modules/xmonad-nix.patch
   ];
   meta = {
     homepage = "http://xmonad.org";

pkgs/applications/window-managers/xmonad/wrapper.nix

@@ -0,0 +1,22 @@
+{ stdenv, buildEnv, ghcWithPackages, xmessage, makeWrapper, packages }:
+
+let
+xmonadEnv = ghcWithPackages (self: [ self.xmonad ] ++ packages self);
+drv = buildEnv {
+  name = "xmonad-with-packages";
+
+  paths = [ xmonadEnv ];
+
+  postBuild = ''
+    # TODO: This could be avoided if buildEnv could be forced to create all directories
+    rm $out/bin
+    mkdir $out/bin
+    for i in ${xmonadEnv}/bin/*; do
+      ln -s $i $out/bin
+    done
+    wrapProgram $out/bin/xmonad \
+      --set XMONAD_GHC "${xmonadEnv}/bin/ghc" \
+      --set XMONAD_XMESSAGE "${xmessage}/bin/xmessage"
+  '';
+  };
+in stdenv.lib.overrideDerivation drv (x : { buildInputs = x.buildInputs ++ [ makeWrapper ]; })

pkgs/development/haskell-modules/configuration-common.nix

@@ -409,6 +409,9 @@ self: super: {
   # https://github.com/seagreen/hjsonschema/issues/4
   hjsonschema = dontCheck super.hjsonschema;
 
+  # Nix-specific workaround
+  xmonad = appendPatch super.xmonad ./xmonad-nix.patch;
+
 } // {
 
   # Not on Hackage.

pkgs/top-level/all-packages.nix

@@ -11805,6 +11805,11 @@ let
 
   xkb_switch = callPackage ../tools/X11/xkb-switch { };
 
+  xmonad-with-packages = callPackage ../applications/window-managers/xmonad/wrapper.nix {
+    ghcWithPackages = haskellngPackages.ghcWithPackages;
+    packages = self: [];
+  };
+
   xmonad_log_applet_gnome2 = callPackage ../applications/window-managers/xmonad-log-applet {
     desktopSupport = "gnome2";
     inherit (xfce) libxfce4util xfce4panel;