Lil' Nestable Clojure REPL

tinyrepl.clj

(def ^:dynamic repl-context)
(defn tinyrepl
  "Simple REPL. :quit to exit."
  [{:keys [prefix layer] :or {prefix "" layer 1} :as context}]
  (let [pre (str prefix ">>>")]
    (with-bindings {#'repl-context (assoc context
                                          :prefix pre
                                          :layer (inc layer))}
      (print (str (ns-name *ns*) (str pre " ")))
      (flush)
      (let [expr (read)
            value (eval expr)]
        (when (not= :quit value)
          (println value)
          (recur))))))

(comment 
  ; Example
  dev=> (tinyrepl {})
  dev>>> (tinyrepl repl-context)
  dev>>>>>> (tinyrepl repl-context)
  dev>>>>>>>>> (+ 1 1)
  2
  dev>>>>>>>>> :quit
  nil
  dev>>>>>> :quit
  nil
  dev>>> :quit
  nil
  dev=>
)