sub list { my ($self,%param) = @_ }
sub shiftit { my $self = shift; my %param = @_ }

cmpthese( -2,{
 list => sub { list( qw(foo bar baz) ) },
 shiftit => sub { shiftit( qw(foo bar baz) ) },
} );
__END__
5.8.3      Rate shiftit    list
shiftit 70621/s      --    -11%
list    79125/s     12%      --
5.6.2      Rate shiftit    list
shiftit 89341/s      --    -10%
list    98866/s     11%      --