http://www.perlmonks.org?node_id=924727


in reply to Re^2: Perl6: What is "idfirst letter"?
in thread Perl6: What is "idfirst letter"?

No. There are special variables with "weird" names ($/, $!, $¢) but they aren't identifiers.

I also don't think that [ counts as an identifier character in Perl 5, because you can't write sub [ { }