anchor.diff: -{ fetchurl, stdenv, zlib, lzo, libtasn1, nettle, pkgconfig
  +{ fetchurl, stdenv, zlib, lzo, libtasn1, nettle, pkgconfig, lzip
   , guileBindings, guile, perl, gmp }:
   
   assert guileBindings -> guile != null;
  
positive.code: 
      homepage = http://www.gnu.org/software/gnutls/;
      license = "LGPLv2.1+";
  
      maintainers = [ stdenv.lib.maintainers.ludo ];
    };
  }
  
  
negative.code:   name = "gnutls-3.1.12";
  
    src = fetchurl {
      url = "ftp://ftp.gnutls.org/gcrypt/gnutls/v3.1/${name}.tar.lz";
      sha256 = "1h8j3xi2jad2dclybgqffb5264hdqrxpsx99irs03yy9np6iw5l8";
    };
  
    # Note: GMP is a dependency of Nettle, whose public headers include
  