anchor.diff:    src = fetchurl {
       urls = tarballUrls version;
       hashOutput = false;
  -    sha256 = "059b3cb69970d8c8c5964caced0335b4af34ac990c8e61f7e3f90cd1c2d11e49";
  +    sha256 = "fea7162d4cca940a387f0587b93f6737d884bf74d8a9d7cfd978bc12cd0b202d";
     };
  -
  -  setupHook = ./setup-hook.sh;
   
     patches = [
       # Do not look in /usr etc. for dependencies.
  
positive.code:     "mirror://cpan/src/5.0/perl-${version}.tar.xz"
    ];
  
    version = "5.28.0";
  in
  stdenv.mkDerivation rec {
    name = "perl-${version}";
  
negative.code:   # Miniperl needs -lm. perl needs -lrt.
    configureFlags = [
      "-de"
      "-Uinstallusrbinperl"
      "-Dinstallstyle=lib/perl5"
      "-Duseshrplib"
      "-Duse64bitall"
      "-Dusethreads"
    ];
  
    configureScript = "./configure.gnu";
  
    setupHook = ./setup-hook.sh;
  
    passthru = {
      libPrefix = "lib/perl5/site_perl";
      srcVerification = fetchurl rec {
        failEarly = true;
        urls = tarballUrls "5.28.1";
        outputHash = "fea7162d4cca940a387f0587b93f6737d884bf74d8a9d7cfd978bc12cd0b202d";
        inherit (src) outputHashAlgo;
        fullOpts = {
          sha256Urls = map (n: "${n}.sha256.txt") urls;
          sha1Urls = map (n: "${n}.sha1.txt") urls;
          md5Urls = map (n: "${n}.md5.txt") urls;
        };
      };
    };
  
    meta = with stdenv.lib; {
      description = "The Perl 5 programmming language";
  