table &mdash; assigning to an
index of a complex number raises an error. Accessing out-of-bound
indexes returns unspecified results, but is guaranteed not to trigger
memory access violations.</li>

<li><b>Indexing a vector</b>: a vector is treated like an array for
indexing purposes, except the vector elements are immutable &mdash;
assigning to an index of a vector raises an error.</li>

</ul>
<p>
A ctype object can be indexed with a string key, too. The only
pre-defined operation is reading scoped constant