OUTER: {
   defined( my $_ = <$fh> ) or last OUTER;

   for (;;) {
      if (/alpha/) {
         f();
         last;
      }

      defined( $_ = <$fh> ) or last OUTER;
   }

   for (;;) {
      g();

      defined( $_ = <$fh> ) or last OUTER;
   }
}