sub foo(\@) {
    my ($array) = @_;
    $_ = uc($_) for @$array;
}

my @array = qw( foo bar Foo Bar );
foo @{ sub { \@_ }->( grep /^[A-Z]/, @array ) };
print "$_\n" for @array;

##</code><code>##

foo
bar
FOO
BAR

##</code><code>##

sub foo {
    $_ = uc($_) for @_;
}

my @array = qw( foo bar Foo Bar );
foo grep /^[A-Z]/, @array;
print "$_\n" for @array;

##</code><code>##

foo
bar
FOO
BAR