feat(nix): support stable nix

default.nix

@@ -0,0 +1,17 @@
+{
+  pkgs ? import nixpkgs {
+    inherit system;
+    config = { };
+    overlays = [ ];
+  },
+  lib ? pkgs.lib,
+  nixpkgs ? <nixpkgs>,
+  system ? builtins.currentSystem,
+}:
+
+let
+  nixForecastPackages = lib.makeScope pkgs.newScope (lib.flip (import ./overlay.nix) pkgs);
+in
+{
+  inherit (nixForecastPackages) nix-forecast;
+}

flake.nix

@@ -129,16 +129,11 @@
         system:
         let
           pkgs = nixpkgsFor.${system};
-          nixForecastPackages = lib.makeScope pkgs.newScope (final: self.overlays.default final pkgs);
+          pkgs' = import ./default.nix { inherit pkgs; };
         in
-        {
-          inherit (nixForecastPackages) nix-forecast;
-          default = self.packages.${system}.nix-forecast;
-        }
+        pkgs' // { default = pkgs'.nix-forecast; }
       );
 
-      overlays.default = final: _: {
-        nix-forecast = final.callPackage ./nix/package.nix { };
-      };
+      overlays.default = final: prev: import ./overlay.nix final prev;
     };
 }

overlay.nix

@@ -0,0 +1,3 @@
+final: _: {
+  nix-forecast = final.callPackage ./nix/package.nix { };
+}