anchor.diff:  
   let
     pname = "TeXmacs";
  -  version = "1.99.14";
  +  version = "1.99.15";
     common = callPackage ./common.nix {
       inherit tex extraFonts chineseFonts japaneseFonts koreanFonts;
     };
  
positive.code: { lib, mkDerivation, callPackage, fetchurl, fetchpatch,
    guile_1_8, qtbase, xmodmap, which, freetype,
    libjpeg,
    sqlite,
  
negative.code: mkDerivation {
    name = "${pname}-${version}";
  
    src = fetchFromGitHub {
      owner = "texmacs";
      repo = "texmacs";
      rev = "v${version}";
      sha256 = "04585hdh98fvyhj4wsxf69xal2wvfa6lg76gad8pr6ww9abi5105";
    };
  
    enableParallelBuilding = true;
  