pkgs-lib.formats: move mkStructuredType to let-block

pkgs/pkgs-lib/formats.nix

@@ -58,6 +58,37 @@ let
     submodule
     ;
 
+  /*
+    Creates a structured value type suitable for serialization formats.
+
+    Parameters:
+    - typeName: String describing the format (e.g. "JSON", "YAML", "XML")
+
+    Returns a type suitable for structured data formats that supports:
+    - Basic types: boolean, integer, float, string, path
+    - Complex types: attribute sets and lists
+  */
+  mkStructuredType =
+    {
+      typeName,
+      nullable ? true,
+    }:
+    let
+      baseType = oneOf [
+        bool
+        int
+        float
+        str
+        path
+        (attrsOf valueType)
+        (listOf valueType)
+      ];
+      valueType = (if nullable then nullOr baseType else baseType) // {
+        description = "${typeName} value";
+      };
+    in
+    valueType;
+
   # Attributes added accidentally in https://github.com/NixOS/nixpkgs/pull/335232 (2024-08-18)
   # Deprecated in https://github.com/NixOS/nixpkgs/pull/415666 (2025-06)
   allowAliases = pkgs.config.allowAliases or false;
@@ -126,37 +157,6 @@ optionalAttrs allowAliases aliases
 
   php = (import ./formats/php/default.nix { inherit lib pkgs; }).format;
 
-  /*
-    Creates a structured value type suitable for serialization formats.
-
-    Parameters:
-    - typeName: String describing the format (e.g. "JSON", "YAML", "XML")
-
-    Returns a type suitable for structured data formats that supports:
-    - Basic types: boolean, integer, float, string, path
-    - Complex types: attribute sets and lists
-  */
-  mkStructuredType =
-    {
-      typeName,
-      nullable ? true,
-    }:
-    let
-      baseType = oneOf [
-        bool
-        int
-        float
-        str
-        path
-        (attrsOf valueType)
-        (listOf valueType)
-      ];
-      valueType = (if nullable then nullOr baseType else baseType) // {
-        description = "${typeName} value";
-      };
-    in
-    valueType;
-
   json =
     { }:
     {