I figured it out! The range operator stuff freaked me out a little, but the big trick is that

foreach my $a (1 .. 5) {
    next while ($a != 2);
}
[download]

won't go to the while it's next to, but the outer foreach loop. Thus, you don't enter an infinite loop.

A curious thing was that I wrote the quick program:

my @strings = ('a', 'b', 'c', 'd', 'e', 'f');
while (my $s = shift @strings) {
    print "Looking at $s\n";
    next while ($s =~ /a/ .. $s =~ /c/);
    print "$s is OK!\n";
}
[download]

How does the range-op-boolean know that $s was a in a previous check. It seems to be maintaining state between invocations.

Update:

my @strings = ('a', 'b', 'c', 'd', 'e', 'f');
while (my $s = shift @strings) {
    print "Looking at $s\n";
    my $value = $s =~ /a/ .. $s =~ /c/;
    print "The value is $value\n";
    next if $value;
    print "$s is OK!\n";
}
[download]

This gives a very interesting output.

Looking at a
The value is 1
Looking at b
The value is 2
Looking at c
The value is 3E0
Looking at d
The value is
d is OK!
Looking at e
The value is
e is OK!
Looking at f
The value is
f is OK!
[download]

I just find that '3E0' thing really odd...