diff --git a/pkgs/applications/editors/vim/default.nix b/pkgs/applications/editors/vim/default.nix
index 71d89f44888f..317fedd902da 100644
--- a/pkgs/applications/editors/vim/default.nix
+++ b/pkgs/applications/editors/vim/default.nix
@@ -1,10 +1,31 @@
-args: 
+args:
+let 
+	defList = [];
+	#stdenv and fetchurl are added automatically
+	notForBuildInputs = []; 
+	getVal = (args.lib.getValue args defList);
+	check = args.lib.checkFlag args;
+	reqsList = [
+	["gtkGUI" "glib" "gtk" "pkgconfig" "libXpm" "libXext" "x11Support"]
+	["athenaGUI" "libXau" "libXt" "libXaw" "libXpm" "libXext" "x11Support"]
+	["x11Support" "libX11"]
+	["hugeFeatures"]
+	["true" "ncurses"]
+	];
+	buildInputsNames = args.lib.filter (x: (null!=getVal x)&&
+		(! args.lib.isInList (notForBuildInputs ++ 
+		["stdenv" "fetchurl" "lib"] ++ 
+		(map builtins.head reqsList)) x)) 
+		/*["libX11" "glib" "gtk" "pkgconfig" "libXpm" "libXext" 
+			"libXau" "libXt" "libXaw" "ncurses"];*/
+		(builtins.attrNames args);
+in
+	assert args.lib.checkReqs args defList reqsList;
 args.stdenv.mkDerivation {
   name = "vim-7.1" +
-	(if ((args ? hugeFeatures) 
-	&& args.hugeFeatures) then 
+	(if (check "hugeFeatures") then 
 	"-huge" else "")
-	+ (if ((args ? libX11)&&(args.libX11 != null))
+	+ (if (check "x11Support")
 	then "-X11" else "")
 	;
  
@@ -15,19 +36,14 @@ args.stdenv.mkDerivation {
  
   inherit (args) ncurses;
 
-  buildInputs =(with ({libX11=null; libXext=null;
-	libSM=null; libXpm=null; libXt=null;
-	libXaw=null; libXau=null; glib=null;
-	gtk=null; pkgconfig=null;
-	} // args); [ncurses] ++
-	(args.lib.filter (x: x != null) 
-	[libX11 libXext libSM libXpm libXt
-	libXaw libXau glib gtk pkgconfig]));
-  
+  debug = builtins.attrNames args;
+  buildInputs = args.lib.filter (x: x!=null) (map getVal buildInputsNames);
+ 
+  preConfigure = "echo \$debug"; 
   postInstall = "ln -s $out/bin/vim $out/bin/vi";
   preBuild="touch src/auto/link.sed";
   configureFlags=" --enable-gui=auto --disable-xim "+
-	(if ((args ? hugeFeatures) && args.hugeFeatures) then 
+	(if (check "hugeFeatures") then 
 	"--with-features=huge --enable-cscope --enable-multibyte --enable-xsmp "
 	else "");
 
diff --git a/pkgs/lib/default.nix b/pkgs/lib/default.nix
index 3b4124fbc279..a6e87b218026 100644
--- a/pkgs/lib/default.nix
+++ b/pkgs/lib/default.nix
@@ -124,6 +124,40 @@ rec {
     then []
     else [first] ++ range (builtins.add first 1) last;
 
-  #Return [arg] or [] for null arg
-        
+  # Return true only if there is an attribute and it is true.
+  checkFlag = attrSet: name:
+	if (name == "true") then true else
+	getAttr [name] false attrSet ;
+
+  logicalOR = x: y: x || y;
+  logicalAND = x: y: x && y;
+
+  # Input : attrSet, [ [name default] ... ], name
+  # Output : its value or default.
+  getValue = attrSet: argList: name:
+  ( getAttr [name] (if argList == [] then null else
+	let x = builtins.head argList; in
+		if (head x) == name then 
+			(head (tail x))
+		else (getValue attrSet 
+			(tail argList) name)) attrSet );
+
+  # Input : attrSet, [[name default] ...], [ [flagname reqs..] ... ]
+  # Output : are reqs satisfied? It's asserted.
+  checkReqs = attrSet : argList : condList :
+  (
+    fold logicalAND true 
+      (map (x: let name = (head x) ; in
+	
+	((checkFlag attrSet name) -> 
+	(fold logicalAND true
+	(map (y: let val=(getValue attrSet argList y); in
+		(val!=null) && (val!=false)) 
+	(tail x))))) condList)) ;
+	
+   
+  isInList = list: x:
+	if (list == []) then false else
+	if (x == (head list)) then true else
+	isInList (tail list) x;
 }
diff --git a/pkgs/tools/package-management/nix/unstable.nix b/pkgs/tools/package-management/nix/unstable.nix
index 97138de923a3..891126128924 100644
--- a/pkgs/tools/package-management/nix/unstable.nix
+++ b/pkgs/tools/package-management/nix/unstable.nix
@@ -6,11 +6,12 @@
 stdenv.mkDerivation {
   name = "nix-0.11pre8816";
   
-  src = fetchurl {
-    url = http://nix.cs.uu.nl/dist/nix/nix-0.11pre8816/nix-0.11pre8816.tar.bz2;
-    md5 = "dd432e6a05179fe30a95c3758e70ac51";
-  };
-  
+  src =   
+	fetchurl {
+		url = http://nix.cs.uu.nl/dist/nix/nix-unstable-latest/nix-0.11pre9063.tar.bz2;
+		sha256 = "0fxsvam0ihzcfg694d28d6b3vkx5klh25jvf3y5igyyqszmmhnxj";
+	};
+
   buildInputs = [perl curl openssl];
 
   configureFlags = "
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index e0838487af30..fa1510973835 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -3345,6 +3345,8 @@ rec {
 	libXt libXaw libXau;
     inherit (gtkLibs) glib gtk;
     hugeFeatures = true;
+    gtkGUI = true;
+    x11Support = true;
   };
 
   vlc = import ../applications/video/vlc {
diff --git a/pkgs/top-level/template-simple.nix b/pkgs/top-level/template-simple.nix
new file mode 100644
index 000000000000..86acd22217d2
--- /dev/null
+++ b/pkgs/top-level/template-simple.nix
@@ -0,0 +1,17 @@
+args:
+args.stdenv.mkDerivation {
+  name = "";
+
+  src = args.fetchurl {
+    url = ;
+    sha256 = "";
+  };
+
+  buildInputs =(with args; []);
+
+  meta = {
+    description = "
+
+";
+  };
+}
diff --git a/pkgs/top-level/template.nix b/pkgs/top-level/template.nix
new file mode 100644
index 000000000000..4f834dd18f18
--- /dev/null
+++ b/pkgs/top-level/template.nix
@@ -0,0 +1,40 @@
+args:
+let 
+	defList = [
+(assert false) - correct it; List element is of form ["name" default]
+	];
+	#stdenv and fetchurl are added automatically
+	notForBuildInputs = [
+(assert false) - correct it; List of names of non-buildInput arguments
+	]; 
+	getVal = (args.lib.getValue args defList);
+	check = args.lib.checkFlag args;
+	reqsList = [
+(assert false) - correct it; List element is of form ["name" "requirement-name" ... ]
+	];
+	buildInputsNames = args.lib.filter (x: (null!=getVal x)&&
+		(! args.lib.isInList (notForBuildInputs ++ 
+		["stdenv" "fetchurl" "lib"] ++ 
+		(map builtins.head reqsList)) x)) 
+		/*["libX11" "glib" "gtk" "pkgconfig" "libXpm" "libXext" 
+			"libXau" "libXt" "libXaw" "ncurses"];*/
+		(builtins.attrNames args);
+in
+	assert args.lib.checkReqs args defList reqsList;
+with args; 
+args.stdenv.mkDerivation {
+  name = "
+#!!! Fill me //
+" ;
+ 
+  src = args.
+#Put fetcher here 
+ 
+  buildInputs = args.lib.filter (x: x!=null) (map getVal buildInputsNames);
+
+  meta = {
+    description = "
+#Fill description here
+";
+  };
+}