I'm dismayed. OK, so this was probably the most fun Perl bug I've ever found. Even today I'm learning new stuff about Perl. Essentially, the flip-flop operator .. which returns false until the left-hand-side returns true, and then true until the right-hand-side returns false keep global state (or that is what I assume.)

Can I reset it (perhaps this would be a good addition to Perl 4-esque hardly ever used reset())? Or, is there no way to use this operator safely?

I also don't see this (the global context bit) documented anywhere in perldoc perlop is this a mistake?

Code

use feature ':5.10';
use strict;
use warnings;

sub search {
    my $arr = shift;
    grep { !( /start/ .. /never_exist/ ) } @$arr;
}

my @foo = qw/foo bar start baz end quz quz/;
my @bar = qw/foo bar start baz end quz quz/;

say 'first shot - foo';
say for search \@foo;

say 'second shot - bar';
say for search \@bar;

Spoiler

$ perl test.pl
first shot
foo
bar
second shot