anchor.diff: -{stdenv, fetchurl, polyml, graphviz, fontconfig, liberation_ttf,
  - experimentalKernel ? true}:
  +{stdenv, fetchurl, polyml, graphviz, experimentalKernel ? true}:
   
   let
     pname = "hol4";
  
positive.code:       --replace "\"/bin/mv\"" "\"mv\"" \
        --replace "\"/bin/cp\"" "\"cp\""
  
      for f in tools/buildutils.sml help/src-sml/DOT;
      do
        substituteInPlace $f --replace "\"/usr/bin/dot\"" "\"${graphviz}/bin/dot\""
      done
  
      #sed -ie "/compute/,999 d" tools/build-sequence # for testing
  
      poly < tools/smart-configure.sml
  
      bin/build ${kernelFlag} -symlink
  
      mkdir -p "$out/bin"
      ln -st $out/bin  "$out/src/${holsubdir}/bin/"*
      # ln -s $out/src/hol4.${version}/bin $out/bin
    '';
  
  
negative.code:     sha256 = "5ce4c1e37301dbc38772694e98f1c7eabf69255908de204b280d8b2b1709e9d0";
    };
  
    buildInputs = [polyml graphviz];
  
    buildCommand = ''
      mkdir -p "$out/src"
      cd  "$out/src"
  
  