Re: [Axiom-developer] Lisp macro fun...

[Waldek Hebisch]

> I have been attempting to generalize Waldek's finite state machine
> using macros, and have essentially run up against the limits of my tiny
> Lisp skills.  Can anybody tell me how to get this thing to expand into
> something like Waldek's code?  (I can provide the whole file if it is
> needed.)
> 

I must admit that I do not understand what you are tring to do now
-- what you posted looks like macro definition, but it contains
(hardcodes) most of had written version.

Have you looked at <http://ll1.ai.mit.edu/shriram-talk.pdf> (it
contains Scheme example of macro-generating finite state
machine)?

Low level macro version of finite state machine may look like:

(automaton
  (setup_code)
  (state normal-start
     (normal_start_setup)
     (-> start-tag-code-1 chunk-start-tag-1)
     (-> newline-code normal-start)
     (default normal))
  (state normal
     (-> newline-code normal-start)
     (default normal))
  (state chunk-start-tag-1
     (-> start-tag-code-2 in-chunk-start-tag
         ;;; Action
         (setf start-pos (+ pos 1)))
  ....

To generate our  code from the above one has to define macros
automaton, state, defalut and ->.  state, defalut and -> may
be local to automaton.  In the above I assumend that we use
chacter codes, but we could also use characters and write:

   (-> #\< chunk-start-tag-1)

A higher level version may do transitions on strings, so you
could write:

   (-> "<<"  in-chunk-start-tag
         ;;; Action
         (setf start-pos (+ pos 1)))

and the macros would automatically generate intermediate states.

-- 
                              Waldek Hebisch
address@hidden