os/overlays/default.nix

{
  self,
  inputs,
  ...
}: {
  flake = {
    nixosModules = rec {
      overlays = ({ ... }: {
        nixpkgs.overlays = [
          (final: prev: let
            unstable = import inputs.nixpkgs-unstable { system = prev.system; };
            master = import inputs.nixpkgs-master { system = prev.system; };
            scan2paperless = import inputs.scan2paperless { system = prev.system; };
          in {
            nixd = unstable.nixd;

            factorio-headless = master.factorio-headless;
            paperless-ngx = master.paperless-ngx;
            waybar = master.waybar;

            scan2paperless = scan2paperless.scan2paperless;

            adlist = inputs.adblock-unbound.packages.${prev.system};

            haskellPackages =
              prev.haskellPackages.override
              (old: {
                overrides = prev.lib.composeExtensions (old.overrides or (_: _: {})) (hfinal: hprev: let
                  version = prev.lib.replaceChars ["."] [""] prev.ghc.version;
                in {
                  # same for haskell packages, matching ghc versions
                  inherit
                    (unstable.haskell.packages."ghc${version}")
                    haskell-language-server
                    ;
                });
              });

            vimPlugins = prev.vimPlugins // {inherit (unstable.vimPlugins) nvim-lspconfig;};
          })
          (import ../pkgs)
          (import ./blesh.nix)
          (import ./manix.nix)
          (import ./rnix-lsp.nix)
          (import ./neovim-plugins.nix)
          (import ./signal-desktop.nix)
        ];
      });
    };
  };
}