anchor.diff:  {stdenv, fetchurl}:
   
  +let
  +  preBuildNoNative = ''
  +      # Make Cwd work on NixOS (where we don't have a /bin/pwd).
  +      substituteInPlace lib/Cwd.pm --replace "'/bin/pwd'" "'$(type -tP pwd)'"
  +    '';
  +  preBuildNative = "";
  +in
   stdenv.mkDerivation {
     name = "perl-5.10.0";
   
  
positive.code:       fi
      '';
  
    preBuild =
      ''
        # Make Cwd work on NixOS (where we don't have a /bin/pwd).
        substituteInPlace lib/Cwd.pm --replace "'/bin/pwd'" "'$(type -tP pwd)'"
      '';
  
    setupHook = ./setup-hook.sh;
  }
  
negative.code:   # "installstyle" option to ensure that modules are put under
    # $out/lib/perl5 - this is the general default, but because $out
    # contains the string "perl", Configure would select $out/lib.
    # Miniperl needs -lm. perl needs -lrt.
    configureFlags = ''
      -de -Dcc=gcc -Uinstallusrbinperl -Dinstallstyle=lib/perl5 -Duseshrplib
      -Dldflags='-lm -lrt'
      ${if stdenv ? glibc then "-Dusethreads" else ""}
    '';
  
  