why wont this workkk

modules/dev/cpp.nix

@@ -0,0 +1,15 @@
+{ config, lib, pkgs, ...}:
+with lib;
+let cfg = config.modules.dev.cpp;
+in {
+  options.modules.dev.cpp = {
+    enable = mkBoolOpt false;
+  };
+
+  config = mkIf cfg.enable {
+    users.users.sako.packages = with pkgs; [
+      cmake
+      gcc
+    ]; 
+  };
+}

modules/dev/default.nix

@@ -0,0 +1,6 @@
+{ config, pkgs, lib, ...}:
+{
+  imports = [
+    ./cpp.nix
+  ];
+}