@{$href}{"one", "two", "three"}; # hash slice, hashref
    @hash   {"one", "two", "three"}; # hash slice, hash

    for (0 .. $#{$aref}) {} # index iteration, arrayref
    for (0 .. $#array)   {} # index iteration, array

    # with references
    @{$aref2} = map  { $href1->{$_} + 1 }
                sort { $href2->{$a} <=> $href2->{$b} }
                grep /foo/, @{$aref1}[0 .. $#{$aref1}/2];

    # without
    @array2 = map  { $hash1{$_} + 1 }
              sort { $hash2{$a} <=> $hash2{$b} }
              grep /foo/, @array1[0 .. $#array1/2];