anchor.diff:    isSystemPkg = x: !isHaskellPkg x;
   
     allPkgconfigDepends = pkgconfigDepends ++ libraryPkgconfigDepends ++ executablePkgconfigDepends ++
  -                        optionals doCheck testPkgconfigDepends ++ optionals doBench benchPkgconfigDepends;
  +                        optionals doCheck testPkgconfigDepends ++ optionals withBenchmarkDepends benchmarkPkgconfigDepends;
   
     propagatedBuildInputs = buildDepends ++ libraryHaskellDepends ++ executableHaskellDepends;
     otherBuildInputs = extraLibraries ++ librarySystemDepends ++ executableSystemDepends ++ setupHaskellDepends ++
                        buildTools ++ libraryToolDepends ++ executableToolDepends ++
                        optionals (allPkgconfigDepends != []) ([pkgconfig] ++ allPkgconfigDepends) ++
                        optionals doCheck (testDepends ++ testHaskellDepends ++ testSystemDepends ++ testToolDepends) ++
  -                     optionals doBench (benchDepends ++ benchHaskellDepends ++ benchSystemDepends ++ benchToolDepends);
  +                     optionals withBenchmarkDepends (benchmarkDepends ++ benchmarkHaskellDepends ++ benchmarkSystemDepends ++ benchmarkToolDepends);
     allBuildInputs = propagatedBuildInputs ++ otherBuildInputs;
   
     haskellBuildInputs = stdenv.lib.filter isHaskellPkg allBuildInputs;
  
positive.code: , src ? fetchurl { url = "mirror://hackage/${pname}-${version}.tar.gz"; inherit sha256; }
  , buildDepends ? [], setupHaskellDepends ? [], libraryHaskellDepends ? [], executableHaskellDepends ? []
  , buildTarget ? ""
  , buildTools ? [], libraryToolDepends ? [], executableToolDepends ? [], testToolDepends ? [], benchToolDepends ? []
  , configureFlags ? []
  , description ? ""
  , doCheck ? !isCross && (stdenv.lib.versionOlder "7.4" ghc.version)
  , doBench ? false
  , doHoogle ? true
  , editedCabalFile ? null
  , enableLibraryProfiling ? false
  
negative.code: // optionalAttrs (preBuild != "")       { inherit preBuild; }
  // optionalAttrs (postBuild != "")      { inherit postBuild; }
  // optionalAttrs (doCheck)              { inherit doCheck; }
  // optionalAttrs (withBenchmarkDepends) { inherit withBenchmarkDepends; }
  // optionalAttrs (checkPhase != "")     { inherit checkPhase; }
  // optionalAttrs (preCheck != "")       { inherit preCheck; }
  // optionalAttrs (postCheck != "")      { inherit postCheck; }
  