anchor.diff:      substitute ${src} $out/bin/vcal \
         --replace /usr/bin/perl ${perl}/bin/perl
       chmod 0755 $out/bin/*
  -    pod2man -n vcal ${src} > $out/share/man/man1/vcal.1
  +    pod2man --name=vcal --release=${version} ${src} > $out/share/man/man1/vcal.1
   
       runHook postInstall
     '';
  
positive.code: 
  stdenv.mkDerivation rec {
    name = "vcal-${version}";
    version = "2.7";
  
    src = fetchurl {
      url    = "http://waynemorrison.com/software/vcal";
      sha256 = "0fknrlad7vb84ngh242xjaq96vkids85ksnxaflk2cr9wcwxfmix";
    };
  
    nativeBuildInputs = [ perl ]; # for pod2man
  
negative.code:   meta = with lib; {
      description = "Parser for VCalendar and ICalendar files, usable from the command line";
      homepage = http://waynemorrison.com/software/;
      license = licenses.asl20;
      maintainers = with maintainers; [ peterhoeg ];
    };
  }
  