{
  description = "A toy implementation of Proof of History (PoH)";

  inputs.nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";

  outputs = inputs:
    let
      systems = [ "x86_64-linux" "aarch64-darwin" ];
      perSystem = f: inputs.nixpkgs.lib.genAttrs systems f;
      systemPkgs = system: import inputs.nixpkgs { inherit system; };
      perSystemPkgs = f: perSystem (system: f (systemPkgs system));
    in
    {
      devShells = perSystemPkgs (pkgs: {
        proof-of-history-dev = pkgs.callPackage ./shell.nix { };
        default = inputs.self.devShells.${pkgs.system}.proof-of-history-dev;
      });
      formatter = perSystemPkgs (pkgs: pkgs.nixpkgs-fmt);
    };
}