title: Combinator /: in scala
body: <p>What is the meaning of this combinator in scala? <code>/:</code></p>
  
  <p>I've found it in several examples:</p>
  
  <pre><code>override def toString(): String = {
      ("" /: cfg) ((str: String, b: BasicBlock) =&gt; str + "Block " + b.id)
    }
  </code></pre>
  
  <p>or</p>
  
  <pre><code>val successorIns = b.getSuccessors().map(in(_))
  val newValue = (top() /: successorIns) (meet(_, _))
  </code></pre>