sub func {}
my $x; sub foo { ++$x }
$x = 0; func foo(), 1,2,3; print "$x\n";  # 1
$x = 0; grep foo(), 1,2,3; print "$x\n";  # 3

##</code><code>##

grep &cb,           ...  === grep { &cb           } ...
grep &cb(),         ...  === grep { &cb()         } ...
grep $cb->(),       ...  === grep { $cb->()       } ...
grep /.../,         ...  === grep { /.../         } ...
grep substr($_, 2), ...  === grep { substr($_, 2) } ...

##</code><code>##

sub mymap (&@) { my ( $code, @list ) = @_; map &$code, @list }

sub get_cb { return sub { uc } }

print(( mymap  \&{ &get_cb }, qw( a b c ) ), "\n");
print(( map    &get_cb,       qw( a b c ) ), "\n");
print(( map    get_cb,        qw( a b c ) ), "\n");
print(( map    get_cb(),      qw( a b c ) ), "\n");

##</code><code>##

ABC
CODE(0x1829a54)CODE(0x1829a54)CODE(0x1829a54)
CODE(0x1829a54)CODE(0x1829a54)CODE(0x1829a54)
CODE(0x1829a54)CODE(0x1829a54)CODE(0x1829a54)