# init the app
   sub _ { 'compile time '.@_};

   my $compile = _(1);
   sub foo { _(1) };

   # finished compiling, so redefine sub _
   sub _ { 'run time '.@_};

   # run the code
   my $run = foo();
   print " $compile - $run\n"

__END__

 compile time 1 - run time 1