Why are you using sum instead of grep here? If you are summing 1 and 0 then the sum will always be the same as the grep answer. For what it's worth I woul disagree that ($_ ? 1 : 0) is clearer in anyway than !!$_. To me the !! version yells bool, while I had to read the ?: version twice before comprehension came. That might be in part because Perl6's new bool context (don't shoot me if that isn't the right wording) lets you ask for a true/false value explicity so thats what I would expext !! to do.