Late in the day, I know, But how about this; Your progy as above with this sub: sub member { my $input = shift; my $list = shift; my @array = (); for (@$list) { $array$_ = 1; } if ($array$input) {return 1} else {return 0}; } Would only work for numerical data so you'd need to test for that but it sounds like that was what you were doing anyway.