Chouser

(ns n01se.externs-for-cljs
  (:require [clojure.java.io :as io]
            [cljs.compiler :as comp]
            [cljs.analyzer :as ana]))

(defn read-file [file]
  (let [eof (Object.)]
    (with-open [stream (clojure.lang.LineNumberingPushbackReader. (io/reader file))]
      (vec (take-while #(not= % eof)
                       (repeatedly #(read stream false eof)))))))

ztellman

;; let's create a simple protocol that just returns a number
user> (defprotocol NumberP (number [_]))
NumberP

;; now we'll create an implementation that always returns '1'
user> (deftype One [] NumberP (number [_] 1))
user.One

;; unsurprisingly, this type only has a single static value, which wraps the '1'
> (-> One .getDeclaredFields seq)