title: What is the proper way to remove elements from a scala mutable map using a predicate
body: <p>How to do that without creating any new collections? Is there something better than this?</p>
  
  <pre><code>val m = scala.collection.mutable.Map[String, Long]("1" -&gt; 1, "2" -&gt; 2, "3" -&gt; 3, "4" -&gt; 4)
  m.foreach(t =&gt; if (t._2 % 2 == 0) m.remove(t._1))
  println(m)
  </code></pre>
  
  <p>P.S. in Scala 2.8</p>