From 584fab5b00d5d6016ba11a30c8e31a6314a5ce65 Mon Sep 17 00:00:00 2001
From: seth <getchoo@tuta.io>
Date: Wed, 30 Aug 2023 13:13:21 -0400
Subject: refactor: don't instantiate nixpkgs

https://zimbatm.com/notes/1000-instances-of-nixpkgs
---
 pkgs/all-packages.nix       | 47 ++++++++++++++++++++++++++-------------------
 pkgs/default.nix            | 15 +++------------
 templates/basic/default.nix | 25 ++++++++++++++++++++++++
 templates/basic/flake.nix   | 35 ++++++++-------------------------
 4 files changed, 63 insertions(+), 59 deletions(-)
 create mode 100644 templates/basic/default.nix

diff --git a/pkgs/all-packages.nix b/pkgs/all-packages.nix
index 6a8f12e..a8b5445 100644
--- a/pkgs/all-packages.nix
+++ b/pkgs/all-packages.nix
@@ -1,21 +1,28 @@
-pkgs: let
-  inherit (pkgs) callPackage;
-in {
-  # original packages
-  cfspeedtest = callPackage ./cfspeedtest.nix {};
-  check-pr = callPackage ./check-pr.nix {};
-  fastfetch = callPackage ./fastfetch.nix {};
-  huion = callPackage ./huion.nix {};
-  klassy = pkgs.libsForQt5.callPackage ./klassy.nix {};
-  mommy = callPackage ./mommy.nix {};
-  nixgc = callPackage ./nixgc.nix {};
-  modrinth-app-unwrapped = callPackage ./modrinth-app {
-    inherit (pkgs.nodePackages) pnpm;
-    inherit (pkgs.darwin.apple_sdk.frameworks) CoreServices Security WebKit;
+{
+  final ? {},
+  prev,
+}: let
+  inherit (prev) callPackage;
+  callPackage' =
+    final.callPackage or prev.lib.callPackageWith (prev // packages);
+
+  packages = {
+    cfspeedtest = callPackage ./cfspeedtest.nix {};
+    check-pr = callPackage ./check-pr.nix {};
+    fastfetch = callPackage ./fastfetch.nix {};
+    huion = callPackage ./huion.nix {};
+    klassy = prev.libsForQt5.callPackage ./klassy.nix {};
+    mommy = callPackage ./mommy.nix {};
+    nixgc = callPackage ./nixgc.nix {};
+    modrinth-app-unwrapped = callPackage ./modrinth-app {
+      inherit (prev.nodePackages) pnpm;
+      inherit (prev.darwin.apple_sdk.frameworks) CoreServices Security WebKit;
+    };
+    modrinth-app = callPackage' ./modrinth-app/wrapper.nix {};
+    treefetch = callPackage ./treefetch.nix {};
+    swhkd = callPackage ./swhkd {};
+    vim-just = callPackage ./vim-just.nix {};
+    xwaylandvideobridge = callPackage ./xwaylandvideobridge.nix {};
   };
-  modrinth-app = callPackage ./modrinth-app/wrapper.nix {};
-  treefetch = callPackage ./treefetch.nix {};
-  swhkd = callPackage ./swhkd {};
-  vim-just = callPackage ./vim-just.nix {};
-  xwaylandvideobridge = callPackage ./xwaylandvideobridge.nix {};
-}
+in
+  packages
diff --git a/pkgs/default.nix b/pkgs/default.nix
index 8471def..cd49eb2 100644
--- a/pkgs/default.nix
+++ b/pkgs/default.nix
@@ -1,22 +1,13 @@
-{
-  self,
-  inputs,
-  ...
-}: {
+_: {
   perSystem = {
     lib,
     pkgs,
     system,
     ...
   }: {
-    _module.args.pkgs = import inputs.nixpkgs {
-      inherit system;
-      overlays = [self.overlays.default];
-    };
-
     packages = let
       p = let
-        packages = import ./all-packages.nix pkgs;
+        packages = import ./all-packages.nix {prev = pkgs;};
       in
         lib.filterAttrs (_: v:
           builtins.elem system (v.meta.platforms or []) && !(v.meta.broken or false))
@@ -25,5 +16,5 @@
       p // {default = p.treefetch;};
   };
 
-  flake.overlays.default = final: _: import ./all-packages.nix final;
+  flake.overlays.default = final: prev: import ./all-packages.nix {inherit final prev;};
 }
diff --git a/templates/basic/default.nix b/templates/basic/default.nix
new file mode 100644
index 0000000..5d0e6a1
--- /dev/null
+++ b/templates/basic/default.nix
@@ -0,0 +1,25 @@
+{
+  lib,
+  stdenv,
+  self,
+  version,
+  ...
+}:
+stdenv.mkDerivation {
+  pname = "hello";
+  inherit version;
+
+  src = self;
+
+  installPhase = ''
+    echo "hi" > $out
+  '';
+
+  meta = with lib; {
+    description = "";
+    homepage = "";
+    license = licenses.mit;
+    maintainers = [maintainers.getchoo];
+    platforms = platforms.linux;
+  };
+}
diff --git a/templates/basic/flake.nix b/templates/basic/flake.nix
index 32fd25b..17943a8 100644
--- a/templates/basic/flake.nix
+++ b/templates/basic/flake.nix
@@ -10,6 +10,7 @@
     nixpkgs,
     ...
   }: let
+    inherit (nixpkgs) lib;
     version = builtins.substring 0 8 self.lastModifiedDate or "dirty";
 
     systems = [
@@ -19,14 +20,13 @@
       "aarch64-darwin"
     ];
 
-    genSystems = nixpkgs.lib.genAttrs systems;
-    nixpkgsFor = genSystems (system:
-      import nixpkgs {
-        inherit system;
-        overlays = [self.overlays.default];
-      });
-
+    genSystems = lib.genAttrs systems;
+    nixpkgsFor = genSystems (sys: nixpkgs.legacyPackages.${sys});
     forAllSystems = fn: genSystems (sys: fn nixpkgsFor.${sys});
+
+    packageFn = pkgs: {
+      hello = pkgs.callPackage ./default.nix {inherit self version;};
+    };
   in {
     devShells = forAllSystems (pkgs: {
       default = pkgs.mkShell {
@@ -43,25 +43,6 @@
       default = pkgs.hello;
     });
 
-    overlays.default = _: prev: {
-      hello = prev.stdenv.mkDerivation {
-        pname = "hello";
-        inherit version;
-
-        src = self;
-
-        installPhase = ''
-          echo "hi" > $out
-        '';
-
-        meta = with prev.lib; {
-          description = "";
-          homepage = "";
-          license = licenses.mit;
-          maintainers = [maintainers.getchoo];
-          platforms = platforms.linux;
-        };
-      };
-    };
+    overlays.default = _: prev: (packageFn prev);
   };
 }
-- 
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