flake: employ pipes!

hosts/default.nix

@@ -31,7 +31,7 @@ inputs: let
           networking.hostName = hostname;
           nixpkgs.hostPlatform = system;
         })
-        (flatten (
+        (
           concatLists [
             # configuration for the host, passed as an argument.
             (singleton ./${hostname}/default.nix)
@@ -39,12 +39,12 @@ inputs: let
             (singleton ./common.nix)
             # Import all files called module.nix from my modules directory.
             (
-              filter (hasSuffix "module.nix") (
-                map toString (listFilesRecursive ../modules)
-              )
+              map toString (listFilesRecursive ../modules)
+              |> filter (hasSuffix "module.nix")
             )
           ]
-        ))
+          |> flatten
+        )
       ];
     };
 in {
@@ -61,8 +61,8 @@ in {
     system = "aarch64-linux";
     hostname = "tower";
   };
-  world = mkSystem {
-    system = "x86_64-linux";
-    hostname = "world";
-  };
+  # world = mkSystem {
+  #   system = "x86_64-linux";
+  #   hostname = "world";
+  # };
 }