refactor: complete overhaul

templates/elm/flake.nix

@@ -1,10 +1,9 @@
 {
   description = "Elm Environment";
-
   inputs = {
     nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+    nixpkgs-stable.url = "github:NixOS/nixpkgs/nixos-23.11";
   };
-
   outputs = inputs @ {
     flake-parts,
     self,
@@ -17,5 +16,13 @@
         ./parts
       ];
       systems = [system];
+      perSystem = {pkgs, ...}: {
+        _module.args.pkgs = import inputs.nixpkgs {
+          inherit system;
+        };
+        _module.args.pkgs-stable = import inputs.nixpkgs-stable {
+          inherit system;
+        };
+      };
     };
 }

templates/elm/parts/config/devshells.nix

@@ -1,4 +1,8 @@
-{pkgs, ...}: {
+{
+  pkgs,
+  pkgs-stable,
+  ...
+}: {
   devShells = {
     default = pkgs.mkShell {
       packages = builtins.attrValues {
@@ -9,7 +13,7 @@
           nil
           ;
         inherit
-          (pkgs.elmPackages)
+          (pkgs-stable.elmPackages)
           elm
           elm-format
           elm-land