[#parsing_error_message]
[section Parsing error message]

A ['parsing error message] is a
[link metaprogramming_value template metaprogramming value] with a
`static std::string get_value()` member function. This function returns the
pretty-printed version of the error the class represents. For example:

  struct example_error
  {
    using type = example_error;
  
    static std::string get_value()
    {
      return "This is a formatted example error."
    }
  };

Failing [link parser parser]s return parsing error messages as error messages.

[endsect]