title: Collection type generated by for with yield
body: <p>When I evaluate a <code>for</code> in Scala, I get an immutable <code>IndexedSeq</code> (a collection with array-like performance characteristics, such as efficient random access):</p>
  
  <pre><code>scala&gt; val s = for (i &lt;- 0 to 9) yield math.random + i
  s: scala.collection.immutable.IndexedSeq[Double] = Vector(0.6127056766832756, 1.7137598183155291, ...
  </code></pre>
  
  <p>Does a <code>for</code> with a <code>yield</code> always return an <code>IndexedSeq</code>, or can it also return some other type of collection class (a <code>LinearSeq</code>, for example)? If it can also return something else, then what determines the return type, and how can I influence it?</p>
  
  <p>I'm using Scala 2.8.0.RC3.</p>