helpers.clj

(ns duckling.helpers
  "This namespace contains the common helpers used in rules")

(defmacro fn& [dim & args-body]
  (let [meta-map (when (-> args-body first map?)
                   (first args-body))
        args-body (if meta-map
                    (rest args-body)
                    args-body)]
    (merge meta-map
      `{:dim ~(keyword dim)
        :pred (fn ~@args-body)})))

(defn dim
  "Returns a func checking dim of a token and additional preds"
  [dim-val & predicates]
  (fn [token]
    (and (= dim-val (:dim token))
      (every? #(% token) predicates))))

(defn integer
  "Return a func (duckling pattern) checking that dim=number and integer=true,
  optional range (inclusive), and additional preds"
  [& [min max & predicates]]
  (fn [token]
    (and (= :number (:dim token))
      (:integer token)
      (or (nil? min) (<= min (:val token)))
      (or (nil? max) (<= (:val token) max))
      (every? #(% token) predicates))))