{
  description = "A flake for building Hello World";

  inputs.nixpkgs.url = github:NixOS/nixpkgs;

  outputs = { self, nixpkgs }: {
    defaultPackage.x86_64-linux =
      with import nixpkgs { system = "x86_64-linux"; };
      stdenv.mkDerivation {
        name = "hello";
        src = self;
        buildPhase = "cc -o hello ./hello.c";
        installPhase = "mkdir -p $out/bin; install -t $out/bin hello";
      };
    defaultPackage.aarch64-darwin =
      with import nixpkgs { system = "aarch64-darwin"; };
      stdenv.mkDerivation {
        name = "hello";
        src = self;
        buildPhase = "cc -o hello ./hello.c";
        installPhase = "mkdir -p $out/bin; install -t $out/bin hello";
      };
  };
}