anchor.diff:  
   let
     pname = "polyml";
  -  version = "5.3";
  +  version = "5.4";
   in
   
   stdenv.mkDerivation {
  
positive.code: 
    src = fetchurl {
      url = "mirror://sourceforge/${pname}/${pname}.${version}.tar.gz";
      sha256 = "154e836f4e65b5c72f8190d3c02e5ed237921cef716cb49add1e0e1e35fb2af4";
    };
  
    meta = {
  
negative.code:     '';
      homepage = http://www.polyml.org/;
      license = "LGPL";
      platforms = with stdenv.lib.platforms; linux;
      maintainers = [ #Add your name here!
        stdenv.lib.maintainers.z77z
      ];
    };
  }
  