It's not legal now, but it may well become so in perl 6 since ?: is becoming ??:: in order to free up the colon (Larry hasn't told us what's going to happen to the question mark, but I wouldn't have a problem with making it a valid character in an identifier. I'd love to be able to write

given $employee {
  when male?   {...}
  when female? {...}
  default { "Ooh... neuter"; ... }
}
[download]

I tend to think that 'question form' methods/functions sit best in a functional or objective programming style; they seem to jar slightly when you're writing procedural stuff. But that could just be me.

Probably what will really happen is that Larry will show us some utterly clear and really useful trick that can be done with '?' as an operator and we'll gleefully use that and forget about using ?s in our identifiers.