anchor.diff:        "-Dlocincpth=${libc}/include"
         "-Dloclibpth=${libc}/lib"
       ]
  -    ++ stdenv.lib.optional (stdenv ? glibc) "-Dusethreads";
  +    ++ optional (stdenv ? glibc) "-Dusethreads";
   
     configureScript = "${stdenv.shell} ./Configure";
   
  
positive.code:     ''
        configureFlags="$configureFlags -Dprefix=$out -Dman1dir=$out/share/man/man1 -Dman3dir=$out/share/man/man3"
  
        ${stdenv.lib.optionalString stdenv.isArm ''
          configureFlagsArray=(-Dldflags="-lm -lrt")
        ''}
      '';
  
    preBuild = stdenv.lib.optionalString (!(stdenv ? gcc && stdenv.gcc.nativeTools))
      ''
        # Make Cwd work on NixOS (where we don't have a /bin/pwd).
        substituteInPlace dist/Cwd/Cwd.pm --replace "'/bin/pwd'" "'$(type -tP pwd)'"
  
negative.code:   libc = if stdenv.gcc.libc or null != null then stdenv.gcc.libc else "/usr";
  
  in
  
  with {
    inherit (stdenv.lib) optional optionalString;
  };
  
  stdenv.mkDerivation rec {
    name = "perl-5.16.3";
  