Remove non-default settings when hydrating

modules/base/nixos-options-to-settings-schema.nix

@@ -28,7 +28,7 @@ let
   evalString = str: builtins.scopedImport {} (builtins.toFile "expr.nix" str);
 
   convertDefaultValue = value:
-    if value._type == "literalExpression" then builtins.toJSON (evalString value.text)
+    if value._type == "literalExpression" then evalString value.text
     else builtins.throw "Can't handle this default value: ${toString value}.";
 
 in

nix/makeEnvironment.nix

@@ -19,14 +19,18 @@ with lib;
 
 let
   evaluated = (callPackage ./evaluate-config.nix { inherit pkgsStable pkgsMaster; }) config;
+  removeNonDefaultSettings = callPackage ./remove-non-default-settings.nix {};
 
   builtExporters = evaluated.config.builtExporters;
   builtKernels = mapAttrs (_: kernel:
     kernel.overrideAttrs (old: {
       passthru = old.passthru // {
         name = "kernels." + kernel.name;
+
         # channel = kernel.channel;
         channel = "codedown";
+
+        settings = removeNonDefaultSettings kernel.settingsSchema kernel.settings;
       };
     })) evaluated.config.builtKernels;
   builtLanguageServers = evaluated.config.builtLanguageServers;

nix/remove-non-default-settings.nix

@@ -0,0 +1,26 @@
+{ lib }:
+
+settingsSchema:
+
+settings:
+
+with lib;
+
+let
+  evalString = str: builtins.scopedImport {} (builtins.toFile "expr.nix" str);
+
+  getSettingsRow = schemaItem: value:
+    if value != schemaItem.defaultValue
+    then { name = concatStringsSep "." schemaItem.target; inherit value; }
+    else null
+  ;
+
+  tryGetSettingsRow = schemaItem:
+    if hasAttrByPath schemaItem.target settings
+    then getSettingsRow schemaItem (getAttrFromPath schemaItem.target settings)
+    else null
+  ;
+
+in
+
+listToAttrs (filter (x: x != null) (map tryGetSettingsRow settingsSchema))