fix nix deps

shell.nix

@@ -1,6 +1,14 @@
-{ pkgs ? import <nixos-unstable> {} }:
+{ pkgs ? import <nixos-unstable> {} } :
+{
 
-  pkgs.mkShell {
+  pkgs = import (builtins.fetchGit {
+      name = "nixos-23.05";
+    url = "https://github.com/nixos/nixpkgs/";
+    ref = "refs/heads/nixos-unstable";
+    rev = "ef99fa5c5ed624460217c31ac4271cfb5cb2502c";
+  });
+
+  foo = pkgs.mkShell {
     # nativeBuildInputs is usually what you want -- tools you need to run
     nativeBuildInputs = with pkgs.buildPackages; [ 
 
@@ -17,6 +25,7 @@
         echo -e "\n run: './make build' to build all (haxe parser + js)\n"
         echo -e "\n run: './make build javascript' to build js\n"
     '';
+  };
 }