fsm.arc

; call: (mktransition '(a more)
; expansion:
; (a (more (cdr str)))
(def mktransition (tn) (list (car tn) (list (last tn) '(cdr str))))

; call:
; (mktransitions '((a more)
;                  (d more)
;                  (r end)))
; expansion:
; (a (more (cdr str))
;  d (more (cdr str))
;  r (end  (cdr str)))
(def mktransitions (ts)
  (accum accfn ; accum helps splice the result of mktransition
    (each x (map1 mktransition ts)
      (accfn (car x))
      (accfn (last x)))))

; call:
; (mkrule '(more (a more) (d more) (r end)))
; expansion:
;  more (fn (str)
;         (if (empty str)
;           t
;           (case (car str)
;             a (more (cdr str))
;             d (more (cdr str))
;             r (end  (cdr str)))))
(mac mkrule (r)
  (let i r
    `(list (car ,i) (fn (str)
                      (if (empty str) t
                        (case (car str)
                          ,@(mktransitions (cdr i))))))))

; example call:
; (automaton 'init
;            '((init (c more))
;              (more (a more)
;                    (d more)
;                    (r end))
;              (end)))
(mac automaton (i r) `(withr/p ,(map1 [mkrule _] r) ,i))