title: How to skip optional parameters in Scala?
body: <p>Given the following function with optional parameters:</p>
  
  <pre><code>def foo(a:Int = 1, b:Int = 2, c:Int = 3) ...
  </code></pre>
  
  <p>I want to keep the default value of <em>a</em> but pass new values to <em>b</em> and <em>c</em> only by positional assignment (rather than by a named assignment), that is any of the following syntaxes would be nice:</p>
  
  <pre><code>foo( , 5, 7)
  foo(_, 5, 7)
  </code></pre>
  
  <p>Is something like that possible with Scala?</p>