anchor.diff:  { stdenv, fetchurl }:
   
   stdenv.mkDerivation rec {
  -  name = "gprolog-1.4.0";
  +  name = "gprolog-1.4.1";
   
     src = fetchurl {
       urls = [
         "mirror://gnu/gprolog/${name}.tar.gz"
         "http://www.gprolog.org/${name}.tar.gz"
       ];
  -    sha256 = "1l66k66ryfw1nfi2wlvsyq4cmr6mm95f4iay1fxdk3hdk3fjyjl0";
  +    sha256 = "e2819ed9c426138d3191e4d97ae5121cf97e132eecf102400f87f1e372a05b72";
     };
   
     configurePhase = "cd src ;"
  
positive.code:     + "--with-examples-dir=$out/share/doc/${name}/examples "
      + "--with-doc-dir=$out/share/doc/${name}";
  
    doCheck = true;
  
    postInstall = ''
      ln -vs "$out/share/${name}/include" "$out/include"
    '';
  
    meta = {
      homepage = http://www.gnu.org/software/gprolog/;
  
      description = "GNU Prolog, a free Prolog compiler with constraint solving over finite domains";
  
      longDescription = ''
        GNU Prolog is a free Prolog compiler with constraint solving
  
negative.code:       declarativity of logic programming.
      '';
  
      maintainers = [ stdenv.lib.maintainers.simons ];
      platforms = stdenv.lib.platforms.gnu;
    };
  