anchor.diff:  { stdenv, fetchurl, flex, bison, pkgconfig, zlib, libtiff, libpng, fftw
   , cairo, readline, ffmpeg, makeWrapper, wxGTK30, netcdf, blas
  -, proj, gdal, geos, sqlite, postgresql, mysql, python2Packages
  +, proj, gdal, geos, sqlite, postgresql, mysql, python2Packages, libLAS
   }:
   
   stdenv.mkDerivation {
  
positive.code:     "--with-mysql-includes=${mysql.connector-c}/include/mysql"
      "--with-mysql-libs=${mysql.connector-c}/lib/mysql"
      "--with-blas"
    ];
  
    # Otherwise a very confusing "Can't load GDAL library" error
  
negative.code: 
    nativeBuildInputs = [ pkgconfig ];
    buildInputs = [ flex bison zlib proj gdal libtiff libpng fftw sqlite cairo
    readline ffmpeg makeWrapper wxGTK30 netcdf geos postgresql mysql.connector-c blas
    libLAS ]
      ++ (with python2Packages; [ python dateutil wxPython30 numpy ]);
  
    # On Darwin the installer tries to symlink the help files into a system
  