anchor.diff:      rev = "a277dc4e55ded3e3ea27dab1e4faf98c112442df";
       sha256 = "1yh5a8l4ship36hwmgmp2kl72s5ac9r8ly1qcs650xv2g9q7yhnq";
     };
  -in
   
  -stdenv.mkDerivation rec {
  +in stdenv.mkDerivation rec {
     pname = "arrow-cpp";
     version = "0.15.0";
   
     src = fetchurl {
  -    url = "mirror://apache/arrow/arrow-${version}/apache-arrow-${version}.tar.gz";
  +    url =
  +      "mirror://apache/arrow/arrow-${version}/apache-arrow-${version}.tar.gz";
       sha256 = "0n7xrn5490r2snjl45pm2a4pr2x8a29sh8mpyi4nj5pr9f62s1yi";
     };
   
  
positive.code:     # From
      # ./cpp/cmake_modules/ThirdpartyToolchain.cmake
      # ./cpp/thirdparty/versions.txt
      url = "https://github.com/jemalloc/jemalloc/releases/download/5.2.0/jemalloc-5.2.0.tar.bz2";
      sha256 = "1d73a5c5qdrwck0fa5pxz0myizaf3s9alsvhiqwrjahdlr29zgkl";
    };
  
    patches = [
      # patch to fix python-test
      ./darwin.patch
      ];
  
    nativeBuildInputs = [ cmake autoconf /* for vendored jemalloc */ flatbuffers ]
      ++ stdenv.lib.optional stdenv.isDarwin fixDarwinDylibNames;
    buildInputs = [
      boost brotli double-conversion flatbuffers gflags glog gtest lz4 rapidjson
      snappy thrift uriparser zlib zstd python.pkgs.python python.pkgs.numpy
    ];
  
    preConfigure = ''
  
negative.code: { stdenv, fetchurl, fetchFromGitHub, fixDarwinDylibNames, autoconf, boost
  , brotli, cmake, double-conversion, flatbuffers, gflags, glog, gtest, lz4, perl
  , python, rapidjson, snappy, thrift, uriparser, which, zlib, zstd }:
  
  let
    parquet-testing = fetchFromGitHub {
  