title: Microsoft Collections for .NET
body: <p>.NET comes with some built in collections (stack, queue, dictionary, list etc.) but others common collections, like priority queues, are missing. There are many third party collection libraries on NuGet but I was wondering if there is an official Microsoft one (like the BCL immutable collections now called <code>System.Collections.Immutable</code>) library with things like (mutable) priorities queues?</p>
  
  <p>EDIT: Important clarification (comment by @rmunn):</p>
  
  <blockquote>
    <p>This question is not asking to recommend a library for X, it is asking
    a factual question, "Are there any official Microsoft libraries for
    X?"</p>
  </blockquote>