anchor.diff:        cp -vs ${static-exe}/bin/tttool $out/linux
         cp -vs ${windows-exe}/bin/tttool.exe $out/
         mkdir $out/osx
  -      cp -vsr ${osx-exe-bundle}/bin/osx $out/osx
  +      cp -vsr ${osx-exe-bundle}/bin/osx/* $out/osx
         cp -vs ${os-switch} $out/tttool
         mkdir $out/contrib
         cp -vsr ${contrib}/* $out/contrib/
  
positive.code:     '';
    };
  
  in
  
  let
  
negative.code:     case "$OSTYPE" in
        linux*)   exec "$(dirname "$0")/linux/tttool" "$@" ;;
        darwin*)  exec "$(dirname "$0")/osx/tttool" "$@" ;;
        msys*)    exec "$(dirname "$0")/tttool.exe" "$@" ;;
        cygwin*)  exec "$(dirname "$0")/tttool.exe" "$@" ;;
        *)        echo "unsupported operating system $OSTYPE" ;;
      esac
    '';
  