let 
  pkgs = import <nixpkgs> {};
  inherit (pkgs) stdenv fetchurl;
in 
stdenv.mkDerivation (finalAttrs: {
  pname = "hello";
  version = "2.2";
  src = fetchurl {
    url = "https://ftp.gnu.org/gnu/hello/hello-${finalAttrs.version}.tar.gz";
    hash = "sha256-aaKGGx/OxlfBoOyKh704+48AcqHewIX91WU9qsm+V1E=";
  };
})