anchor.diff:  { lib, stdenv
   , fetchurl, unzip
   , hdf5
  +, libxml2
   , m4
   , curl # for DAP
   , removeReferencesTo
  
positive.code:   inherit (hdf5) mpiSupport mpi;
  in stdenv.mkDerivation rec {
    pname = "netcdf" + lib.optionalString mpiSupport "-mpi";
    version = "4.8.1";
  
    src = fetchurl {
      url = "https://downloads.unidata.ucar.edu/netcdf-c/${version}/netcdf-c-${version}.tar.gz";
      sha256 = "1cbjwjmp9691clacw5v88hmpz46ngxs3bfpkf2xy1j7cvlkc72l0";
    };
  
    postPatch = ''
  
negative.code:   '';
  
    nativeBuildInputs = [ m4 removeReferencesTo ];
  
    buildInputs = [
      curl
      hdf5
      libxml2
      mpi
    ];
  
    passthru = {
      inherit mpiSupport mpi;
  