in reply to Confused Monkey
I believe that perl poems *should* compile without errors; however, "Perl poems" are cultural and community inceptions, and are not an integral, or specificational, part of the language.
As such, there is no rule that says they should or shouldn't compile, and it's the prerogative of composer of a Perl poem to choose whether to adhere to this convention or not.
I also believe that, Wikipedia artices, which are written by whomever wishes to, should not be treated as definitive.
"A core tenant of the greater Perl philosophy is to trust that the developer knows enough to solve the problem" - Jay Shirley, A case for Catalyst.