anchor.diff:      sha256 = "1rn03rqlf1iv6n87a78hkda2yqparhhaivfjpizblmxvlw2hk5r8";
     };
   
  +  url = if stdenv.isLinux
  +    then "https://releases.hashicorp.com/vagrant/${version}/vagrant_${version}_${arch}.deb"
  +    else if stdenv.isDarwin
  +      then "https://releases.hashicorp.com/vagrant/${version}/vagrant_${version}.dmg"
  +      else "system ${stdenv.system} not supported";
  +
     sha256 = {
  -    "x86_64-linux" = "1nkhf160hcl02yvafj6hq53j204qqxyvxjngnmf4f5md8dmkpn76";
  -    "i686-linux"   = "0mr4pn7nggjdsqyxh1z2mflvvmpzhbxh5gax501d2hi8xr0y68df";
  +    "x86_64-linux"  = "1nkhf160hcl02yvafj6hq53j204qqxyvxjngnmf4f5md8dmkpn76";
  +    "i686-linux"    = "0mr4pn7nggjdsqyxh1z2mflvvmpzhbxh5gax501d2hi8xr0y68df";
  +    "x86_64-darwin" = "1nd2adxwhs2vwmi5vw2z720ny4q9rpj8i4dlcdxzbyli7h8cs5mr";
     }."${stdenv.system}" or (throw "system ${stdenv.system} not supported");
   
     arch = builtins.replaceStrings ["-linux"] [""] stdenv.system;
  
positive.code:   postFixup = ''
      chmod +x "$out/opt/vagrant/embedded/gems/gems/bundler-1.12.5/lib/bundler/templates/Executable"
      chmod +x "$out/opt/vagrant/embedded/gems/gems/vagrant-$version/plugins/provisioners/salt/bootstrap-salt.sh"
    '';
  }
  
negative.code: { stdenv, fetchurl, fetchpatch, dpkg, curl, libarchive, openssl, ruby, buildRubyGem, libiconv
  , libxml2, libxslt, makeWrapper, p7zip, xar, gzip, cpio }:
  
  let
    version = "1.8.6";
  