Big breaking change. I have radically reduced number of nulls used in all-packages.nix and generally switched to composedArgsAndFun which simply adds .meta.function to everything that has come through it.. I have not tested the build, because OO.o has to be updated...

svn path=/nixpkgs/trunk/; revision=12625

pkgs/games/construo/0.2.2.nix

@@ -7,7 +7,7 @@ args : with args;
 		};
 
 		buildInputs = [libX11 zlib xproto]
-		++ (if args ? mesa then [mesa freeglut] else [])
+		++ (if args ? mesa then [args.mesa args.freeglut] else [])
 		;
 		configureFlags = [""];
 	} null; /* null is a terminator for sumArgs */

pkgs/lib/default.nix

@@ -32,6 +32,13 @@ rec {
 	else (innerComposedArgs f (y x))));
   composedArgs = f: innerComposedArgs f {};
 
+  sumTwoArgs = f: x: y: (f (x // y));
+  composedArgsAndFun = f : x : (f x) // {
+    meta = {
+      function = composedArgsAndFun (sumTwoArgs f x);
+    };
+  };
+
   # example a = pairMap (x : y : x + y) ["a" "b" "c" "d"];
   # result: ["ab" "cd"]
   innerPairMap = acc: f: l: