anchor.diff: -{ stdenv
  +{ stdenv, lib
   , fetchFromGitHub
   , fixDarwinDylibNames
   , which, perl
  
positive.code: 
  let
    malloc = if jemalloc != null then jemalloc else gperftools;
  in
  stdenv.mkDerivation rec {
    name = "rocksdb-${version}";
    version = "5.10.3";
  
    outputs = [ "dev" "out" "static" ];
  
    src = fetchFromGitHub {
      owner = "facebook";
  
negative.code:   buildFlags = buildAndInstallFlags ++ [
      "shared_lib"
      "static_lib"
    ] ++ tools ;
  
    installFlags = buildAndInstallFlags ++ [
      "INSTALL_PATH=\${out}"
  