</a></span><a class="link" href="lexer_quickstart1.html#spirit.lex.tutorials.lexer_quickstart1.doing_the_useful_work">Doing
          the Useful Work</a>
        </h6>
<p>
          We will use a setup, where we want the <span class="emphasis"><em>Spirit.Lex</em></span>
          library to invoke a given function after any of the generated tokens is
          recognized. For this reason we need to implement a functor taking at least
          the generated token as an argument and returning a boolean value