sub working
{
    my @a = (1);
    grep { print "grep\n"; return 'leave' } @a;
    print "Still here #1\n";
}
working;

__DATA__
grep

##</code><code>##

sub mygrep (&@) {
    my $code = shift;
    my @result;
    foreach $_ (@_) {
        push(@result, $_) if &$code;
    }
    @result;
}

sub notworking
{
    my @a = (1);
    mygrep { print "mygrep\n"; return 'leave' } @a;
    print "Still here #2\n";
}

notworking;

__DATA__
mygrep
Still here #2