while( my $next = $iter->() ) {
    my @next = @$next;
    ...
}

##</code><code>##

while( my @next = @{ $iter->() } ) {
    ...
}

##</code><code>##

while( my $next = $iter->() ) {
    ($next) = @$next;
    ...
}

##</code><code>##

while( my $next = @{ $iter->() } ) {
    ...
}

##</code><code>##

while( my ($next) = $iter->() ) {
    ...
}