lib: set as fixed point

lib/default.nix

@@ -1,7 +1,9 @@
-# All of the custom functions suitable for all environments.
+# The entrypoint for our custom library set.
 { lib }:
 
-rec {
+lib.makeExtensible
+  (self:
+    rec {
       /* Count the attributes with the given predicate.
 
          Examples:
@@ -15,7 +17,26 @@ rec {
         lib.count (attr: pred attr.name attr.value)
           (lib.mapAttrsToList lib.nameValuePair attrs);
 
+      /* Returns the file path of the given config of the given environment.
+
+         Type: getConfig :: String -> String -> Path
+
+         Example:
+           getConfig "home-manager" "foo-dogsquared"
+           => ../configs/home-manager/foo-dogsquared
+      */
       getConfig = type: config: ../configs/${type}/${config};
 
+
+      /* Returns the file path of the given user subpart of the given
+         environment. Only certain environments such as NixOS have this type of
+         setup.
+
+         Type: getConfig :: String -> String -> Path
+
+         Example:
+           getUser "nixos" "foo-dogsquared"
+           => ../configs/nixos/_users/foo-dogsquared
+      */
       getUser = type: user: ../configs/${type}/_users/${user};
-}
+    })