Hmm. After experimenting (albeit with 5.5.3, the most recent usable release), I have seen that:

foreach (map $_, @a) {
  $_++; # then whatever
}
[download]

is sufficient. Cool, I'll add that to my trick bag. Much easier than that crazy nested @{[@a]} I've seen so often (and think I actually invented from first principles at one point).

-- Randal L. Schwartz, Perl hacker