gistfile1.txt

(ns ptest.core
  (:require [the.parsatron :as p]))

(p/defparser op []
  (p/choice (p/char \+)
            (p/char \-)))

(p/defparser number []
  (p/let->> [d (p/many (p/digit))]
            (p/always (reduce str d))))

(declare e2)

(p/defparser e []
  (p/>> (number) (e2)))

(p/defparser e2 []
  (p/choice (p/>> (op) (e))
            (p/always nil)))


(declare expr)
(declare expr2)

(p/defparser expr []
  (p/choice
   (expr2)
   (p/let->> [x (number)]
             (p/choice (p/let->> [o (op),
                                  y (expr)]
                                 (p/always (list x o y)))
                       (p/always x)))))

(p/defparser expr2 []
  (p/let->> [c1 (p/char \(),
             e (expr),
             c2 (p/char \))]
            (p/always (list "[" e "]"))))