{
  inputs = {
    nixpkgs.url = github:NixOS/nixpkgs/nixos-unstable;
    nixos-hardware.url = github:NixOS/nixos-hardware;
    darwin.url = github:lnl7/nix-darwin/master;
    darwin.inputs.nixpkgs.follows = "nixpkgs";
    home-manager.url = github:nix-community/home-manager;
    home-manager.inputs.nixpkgs.follows = "nixpkgs";
    emacs-overlay.url = github:nix-community/emacs-overlay;
    secrets = {
      url = git+ssh://git.alanpearce.eu/nixfiles-private;
      flake = false;
    };
  };

  outputs = {
    self,
    darwin,
    emacs-overlay,
    home-manager,
    nixpkgs,
    secrets,
    ...
  } @ attrs: let
    darwinSystem = "aarch64-darwin";
    darwinPkgs = nixpkgs.legacyPackages.${darwinSystem};
    nixosSystem = "x86_64-linux";
    nixosPkgs = nixpkgs.legacyPackages.${nixosSystem};
    aarch64LinuxSystem = "aarch64-linux";
    aarch64LinuxPackages = nixpkgs.legacyPackages.${aarch64LinuxSystem};
  in {
    nixosConfigurations.prefect = nixpkgs.lib.nixosSystem {
      system = "x86_64-linux";
      specialArgs = attrs;
      modules = [./system/prefect.nix];
    };
    darwinConfigurations.mba = darwin.lib.darwinSystem {
      system = darwinSystem;
      specialArgs = attrs;
      modules = [./system/mba.nix];
    };
    homeConfigurations."alan@mba" = home-manager.lib.homeManagerConfiguration {
      pkgs = darwinPkgs;
      modules = [./user/mba.nix (secrets + "/default.nix")
      ({ nixpkgs.overlays = [emacs-overlay.overlay]; })];
    };
    homeConfigurations."alan@prefect" = home-manager.lib.homeManagerConfiguration {
      pkgs = nixosPkgs;
      modules = [./user/prefect.nix (secrets + "/default.nix")
      ({ nixpkgs.overlays = [emacs-overlay.overlay]; })];
    };
    homeConfigurations."alan@NanoPi.lan" = home-manager.lib.homeManagerConfiguration {
      pkgs = aarch64LinuxPackages;
      modules = [./user/server.nix];
    };
  };
}