anchor.diff:      nlopt
       lp_solve
       colpack
  -  ] ++ lib.optionals pythonSupport (with python2Packages; [ python numpy ])
  +  ] ++ lib.optionals pythonSupport (with python3Packages; [ python numpy ])
       ++ lib.optional opencvSupport opencv;
   
     cmakeFlags = let
  
positive.code: , lp_solve
  , colpack
    # extra support
  , pythonSupport ? true
  , opencvSupport ? false
  , opencv ? null
  , withSvmLight ? false
  }:
  
  assert pythonSupport -> python2Packages != null;
  assert opencvSupport -> opencv != null;
  
  assert (!blas.isILP64) && (!lapack.isILP64);
  
negative.code:     "-DENABLE_TESTING=${enableIf doCheck}"
      "-DDISABLE_META_INTEGRATION_TESTS=ON"
      "-DTRAVIS_DISABLE_META_CPP=ON"
      "-DINTERFACE_PYTHON=${enableIf pythonSupport}"
      "-DOpenCV=${enableIf opencvSupport}"
      "-DUSE_SVMLIGHT=${enableIf withSvmLight}"
    ];
  