>perl -wMstrict -le
"sub D {
   my %defaults = qw(foo 999  bar 888  baz 777);
   ;;
   my ($hr_args) = @_;
   my %arguments = (%defaults, %{ $hr_args || {} });
   ;;
   print qq{foo $arguments{foo}  bar $arguments{bar}  baz $arguments{baz}};
   }
 ;;
 D();
 ;;
 D({bar => 2});
 ;;
 D({baz => 1, foo => 3});
"
foo 999  bar 888  baz 777
foo 999  bar 2  baz 777
foo 3  bar 888  baz 1