anchor.diff:  
   stdenv.mkDerivation rec {
     pname = "vlang";
  -  version = "0.1.21";
  +  version = "weekly.2021.25";
   
     src = fetchFromGitHub {
       owner = "vlang";
       repo = "v";
       rev = version;
  -    sha256 = "0npd7a7nhd6r9mr99naib9scqk30209hz18nxif27284ckjbl4fk";
  +    sha256 = "0y4a5rmpcdqina32d6azbmsbi3zqqfl413sicg72x6a1pm2vg33j";
     };
   
     # V compiler source translated to C for bootstrap.
  
positive.code:   vc = fetchFromGitHub {
      owner = "vlang";
      repo = "vc";
      rev = "950a90b6acaebad1c6ddec5486fc54307e38a9cd";
      sha256 = "1dh5l2m207rip1xj677hvbp067inw28n70ddz5wxzfpmaim63c0l";
    };
  
    enableParallelBuilding = true;
    propagatedBuildInputs = [ glfw freetype openssl ]
      ++ lib.optional stdenv.hostPlatform.isUnix upx;
  
    buildPhase = ''
      runHook preBuild
      cc -std=gnu11 $CFLAGS -w -o v $vc/v.c -lm $LDFLAGS
      ./v -prod -cflags `$CFLAGS` -o v compiler
      # Exclude thirdparty/vschannel as it is windows-specific.
      find thirdparty -path thirdparty/vschannel -prune -o -type f -name "*.c" -execdir cc -std=gnu11 $CFLAGS -w -c {} $LDFLAGS ';'
      runHook postBuild
  
negative.code:     runHook preInstall
      mkdir -p $out/{bin,lib,share}
      cp -r examples $out/share
      cp -r {cmd,vlib,thirdparty} $out/lib
      mv v $out/lib
      ln -s $out/lib/v $out/bin/v
      runHook postInstall
    '';
  