From 16d594a0e2017bfa8b24051f4697d8debc240bfb Mon Sep 17 00:00:00 2001
From: Robert Hensing <robert@roberthensing.nl>
Date: Sun, 7 May 2023 15:27:05 +0200
Subject: [PATCH] lib.types.pkgs: init

A nominal type.
---
 lib/types.nix                                        | 8 ++++++++
 nixos/doc/manual/development/option-types.section.md | 4 ++++
 2 files changed, 12 insertions(+)

diff --git a/lib/types.nix b/lib/types.nix
index e0da18a2febb..373d0ce7876f 100644
--- a/lib/types.nix
+++ b/lib/types.nix
@@ -476,6 +476,14 @@ rec {
       check = x: isDerivation x && hasAttr "shellPath" x;
     };
 
+    pkgs = addCheck
+      (unique { message = "A Nixpkgs pkgs set can not be merged with another pkgs set."; } attrs // {
+        name = "pkgs";
+        descriptionClass = "noun";
+        description = "Nixpkgs package set";
+      })
+      (x: (x._type or null) == "pkgs");
+
     path = mkOptionType {
       name = "path";
       descriptionClass = "noun";
diff --git a/nixos/doc/manual/development/option-types.section.md b/nixos/doc/manual/development/option-types.section.md
index 9e2ecb8e3562..9e156ebff9d3 100644
--- a/nixos/doc/manual/development/option-types.section.md
+++ b/nixos/doc/manual/development/option-types.section.md
@@ -99,6 +99,10 @@ merging is handled.
     problems.
     :::
 
+`types.pkgs`
+
+:   A type for the top level Nixpkgs package set.
+
 ### Numeric types {#sec-option-types-numeric}
 
 `types.int`