my %hash = (
   'a' => 'A',
   'b' => 'B',
   'c' => 'C',  
);

my @array = qw( d e f );

print(join(', ',   @hash{'a', 'b'}   ), "\n");  # A, B
print(join(', ',   @array[0, 1]      ), "\n");  # d, e