From 6f8b4d9ebe00e7b62ce5bff1fb3a9573d976b721 Mon Sep 17 00:00:00 2001
From: Erik Arvstedt <erik.arvstedt@gmail.com>
Date: Thu, 3 Feb 2022 20:46:25 +0100
Subject: [PATCH] flake: optimize nixpkgs importing

`nixpkgs.legacyPackages.${system}` allows reusing a single pkgs instance
that is shared among all flakes with the same `nixpkgs` input.
This is relevant when a user overrides the `nixpkgs` input of our flake
or exports our `nixpkgs` input to other flakes.
`import nixpkgs` would create a new pkgs instance instead.
---
 flake.nix | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/flake.nix b/flake.nix
index 273216c..d27d621 100644
--- a/flake.nix
+++ b/flake.nix
@@ -18,8 +18,8 @@
       lib = {
         mkNbPkgs = {
           system
-          , pkgs ? import nixpkgs { inherit system; }
-          , pkgsUnstable ? import nixpkgsUnstable { inherit system; }
+          , pkgs ? nixpkgs.legacyPackages.${system}
+          , pkgsUnstable ? nixpkgsUnstable.legacyPackages.${system}
         }:
           import ./pkgs { inherit pkgs pkgsUnstable; };
       };
@@ -65,7 +65,7 @@
 
     } // (flake-utils.lib.eachSystem supportedSystems (system:
       let
-        pkgs = import nixpkgs { inherit system; };
+        pkgs = nixpkgs.legacyPackages.${system};
 
         nbPkgs = self.lib.mkNbPkgs { inherit system pkgs; };