title: Why no StringBuilder.+=(String) in Scala?
body: <p>This behavior seems to be broken (I am using Scala 2.9.1)</p>
  
  <pre><code>var b= new StringBuilder
  </code></pre>
  
  <p>These are OK: </p>
  
  <pre><code>b+='a'
  b.append('b') 
  b.append("de")
  </code></pre>
  
  <p>This produces compile error:  </p>
  
  <pre><code>b+="de"
  </code></pre>
  
  <p>Any idea as to why only StringBuilder#+=(c: Char) exists whereas both StringBuilder#append(c:Char) and StringBuilder#append(s:String) happily co-exist? What is wrong with declaring and implementing StringBuilder#+=(s: String)? </p>
  
  <p>Is it oversight or some deeper problem in the Scala type system?</p>