Parser DDSL

Fan’s parser DDSL is fully self-explainable, its runtime has enough meta-data to reconstruct itself.

  • Learn the syntax by yourself

    Suppose you have toplevel installed successfully ( see Toplevel support).

    $ #directory "+fan";;
    $ #load "fanTop.cma";;

    Now if you want to understand what’s the definition for the syntactic category case

    Fgram.print Format.std_formatter ;;

    The output is something like this:

      [ LA
      [ "|"; L1 case0 SEP "|" -> bar_of_list l
      | pat; "->"; exp -> `Case (_loc, p, e)]

    Unlike Camlp4, such grammar printer is the original grammar which is 100% honest to the user’s input, no computation involved.

    So you can install the printer in the toplevel and explore different non-terminals by your self.

    $ #install_printer Fgram.print;;


  • How the parser works
  • Where is the lexer?
  • TODO Functional generation