[jmccrea@juno jmccrea]$ cat testy2

#!perl -ap
split;

[jmccrea@juno jmccrea]$ perl -MO=Deparse testy2

LINE: while (defined($_ = <ARGV>)) {
    @F = split(/\s+/, $_, 0);
    split(/\s+/, $_, 0);
}
continue {
    print $_;
}
testy2 syntax OK

[jmccrea@juno jmccrea]$ cat testy 

#!perl -apF
split;

[jmccrea@juno jmccrea]$ perl -MO=Deparse testy 

LINE: while (defined($_ = <ARGV>)) {
    @F = split(/\n/, $_, 0);
    split(/\s+/, $_, 0);
}
continue {
    print $_;
}
testy syntax OK