title: What are the differences between $, @, % in Perl variable declaration?
body: <p>Example:</p>
  
  <pre><code>my $some_variable;
  my @some_variable;
  my %some_variable;
  </code></pre>
  
  <p>I know, <code>@</code> seems to be for array, <code>$</code> for primitive, is it totally right?
  What is <code>%</code> for?</p>