{
  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-21.05";
    nixos-unstable.url = "github:NixOS/nixpkgs/nixos-unstable";
    home-manager = {
      url = "github:rycee/home-manager/release-21.05";
      inputs.nixpkgs.follows = "nixpkgs";
    }; 
  };
  
  outputs = inputs @ { self, nixpkgs, nixos-unstable, home-manager }: let
    system = "x86_64-linux";

    pkgs = import nixpkgs { 
      inherit system; 
      config.allowUnfree = true; 
      overlays = [ (final: prev: { inherit unstable; }) ];
    };

    unstable = import nixos-unstable { 
      inherit system; 
      config.allowUnfree = true; 
    };

    utils = import ./lib { inherit pkgs unstable nixpkgs nixos-unstable home-manager; };

    inherit (utils) host;
    inherit (utils) user;
  in  {
    nixosConfigurations = {
      architect = host.mkHost { name = "architect"; users = [ { user = "giulio"; roles = []; } ]; };
      gAluminum = host.mkHost { name = "gAluminum"; users = [ { user = "giulio"; roles = [ "desktop" "ssh" "git" ]; } ]; roles = [ "gnome" ]; };
      proxy = host.mkHost { name = "proxy"; };
    };
  };
}