use zig overlay

flake.nix

@@ -1,44 +1,41 @@
 {
   description = "FabApp";
 
+  # Inspired by https://github.com/mitchellh/zig-objc/blob/main/flake.nix
   inputs = {
     # take unstable if not specified
     # nixpkgs.url = "github:nixos/nixpkgs/release-23.05";
-    flake-parts.url = "github:hercules-ci/flake-parts";
+    # nixpkgs.url = "github:NixOS/nixpkgs/unstable";
+    flake-utils.url = "github:numtide/flake-utils";
+    zig.url = "github:mitchellh/zig-overlay";
   };
 
-  outputs = inputs@{ flake-parts, nixpkgs, ... }:
-    flake-parts.lib.mkFlake { inherit inputs; } {
-      flake = {
-        # Put your original flake attributes here.
-      };
-
-      systems = [ "x86_64-linux" ];
-
-      # https://flake.parts/module-arguments.html#persystem-module-parameters
-      perSystem = { pkgs, system, ... }: {
-        _module.args.pkgs = import nixpkgs {
-          inherit system;
-          # config.allowUnfree = true;
+  outputs = {
+    self,
+    nixpkgs,
+    flake-utils,
+    ...
+  } @ inputs: let
+    overlays = [
+      (final: prev: {
+        zigpkgs = inputs.zig.packages.${prev.system};
+      })
+    ];
+    systems = ["x86_64-linux"];
+  in
+    flake-utils.lib.eachSystem systems (
+      system: let
+        pkgs = import nixpkgs {inherit overlays system;};
+      in rec {
+        devShells.default = pkgs.mkShell {
+          nativeBuildInputs = with pkgs; [
+            zigpkgs.master
+            zls
+            emscripten
+            sqlite
+          ];
         };
-
-        devShells.default = with pkgs;
-          mkShell {
-            buildInputs = [
-              sqlite
-
-              # Zig / webAssembly impl.
-              zig
-              zls
-              emscripten
-
-              # Tools
-              nixfmt
-            ];
-
-          };
-
-        formatter = pkgs.nixfmt;
-      };
-    };
+        formatter = pkgs.alejandra;
+      }
+    );
 }