The result is produced by using the update operator //. This means nested values of previous overlays are not merged recursively. In other words, previously defined attributes are replaced, ignoring the previous value, unless referenced by the overlay; for example final: prev: { foo = final.foo + 1; }.

The result is produced by using the update operator //. This means nested values of previous overlays are not merged recursively. In other words, previously defined attributes are replaced, ignoring the previous value, unless referenced by the overlay; for example final: prev: { foo = final.foo + 1; }.

In reply to @k900:0upti.me
You don't need a flake for this

Because after a lot of fiddling I've got a flake that looks like this:

{
  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable"; # or a stable version
    # Poetry required to build this flake
    poetry2nix.url = "github:nix-community/poetry2nix";
  };

  outputs = { self, nixpkgs, poetry2nix }: {
    packages.x86_64-linux.mypackage = with nixpkgs;
    # The little incantation to use poetry2nix
      let
        system = "x86_64-linux";
        pkgs = legacyPackages.${system};
        poetry2nixLib = poetry2nix.lib.mkPoetry2Nix { inherit pkgs; };
      in poetry2nixLib.mkPoetryApplication rec {
        pname = "mypackage";
        version = "3.2.5";

        # Attempt to fetchFromGitHub as the source dir
        projectDir = pkgs.fetchFromGitHub {
          ...
        };

        meta = with lib; {
          ...
        };
      };
  };
}

and it's just giving me a recursion error