title: Using Positional and positioned() in scala parser combinators
body: <p>With separate Lexer and Parser ...</p>
  
  <pre><code>class YamlLexical extends StdLexical with YamlTokens with RegexParsers {...
  object YamlParser extends StdTokenParsers with YamlTokens with PackratParsers {...
  </code></pre>
  
  <p>... how to get the position of the parsed string into AST classes?</p>
  
  <pre><code>(... positioned(elem(...)) * ... )^^ { ... =&gt; List( Ast(startpos, parsedtext, ... subnodes ... ), ... )}
  </code></pre>