error.clj

;; Anything you type in here will be executed
;; immediately with the results shown on the
;; right.
(defprotocol IState
  (-patch [state delta])
  (-diff [from to]))

(defprotocol IDiff
  (-apply [diff state]))

(defprotocol IEmpty
  (-empty [_]))

(defn patch
  [state diff]
  (-apply diff state))

(defn diff
  [from to]
  (-diff from to))


(defmacro defmodel
  [id record]
  (let [fields (keys record)
        defaults (vals record)
        attributes (vec (map #(symbol (name %)) fields))]
    `(defrecord ~id ~attributes
       IEmpty
       (-empty [model] (new ~id ~@defaults))
       IState
       (-patch [state diff]
               (let [updated# (set (keys diff))
                     values# (map (fn [key#]
                                    (if (updated# key#)
                                      (patch (key# state) (key# diff))
                                      (key# state)))
                                 ~fields)]
                    (vector values#))))))



(defmodel Task {:id 0
                :description ""
                :completed false
                :editing false})


;; clojure.lang.Compiler$CompilerException: java.lang.RuntimeException: No such var: user/state, compiling:(null:36:46)