parser.clj

(defmonad
  :name    :parser
  :do      parsing
  :bind    (fn [mv f]
	     (fn [s]
	       (when-let [[v s*] (mv s)]
		 ((f v) s*))))
  :return  (fn [v] (fn [s] [v s]))
  :zero    (fn [s] nil)
  :plus    (fn [a b] (fn [s] (or (a s) (b s))))
  :modules [base state maybe])

;;;; snip

(defparser identifier
  a <- ident-start
  b <- (zero-or-more (<> ident-start ident-cont))
  c <- spacing
  (return (symbol (apply str (cons a b)))))

;; string literals
(def escape-map
     {\\ \\
      \r \return
      \n \newline
      \f \formfeed
      \t \tab
      \" \"})

(defparser escape-char
  a <- BACKSLASH
  b <- (any-of "\"\\bntfr")
  (return (escape-map b)))

(defparser string
  a <- QUOTE
  b <- (zero-or-more (<!> QUOTE (<> escape-char any)))
  c <- QUOTE
  (return (apply str b)))

(defparser (not-followed-by A B)
  a <- A
  s <- get-state
  :when-not (B s)
  (return a))

(defn delimited-by
  [open close between]
  (fmap second (m-seq open between close)))