Is there an data type that acts both as a list and a dictionary?
<p>Normally when I need to have a list of ints/strings/etc. I create a list like:</p>

<pre><code>var list = new List&lt;string&gt;
</code></pre>

<p>And then I create a hashtable that contains all the strings, and I don't insert into the list unless it isn't in the hashtable i.e. to enforce unique items in the list.</p>

<p>Is there a datatype that can satisfy both of these requirements for me?</p>
