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(require '[clojure.string :as s]
         '[gregor.core :as gregor])

(defn to-prop [k]
  (-> k name (s/replace #"-" ".")))

(defn to-props
  "ranames keys by converting them to strings and substituting dashes with periods
   only does top level keys"
  [conf]

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abstract

Clojure is powerful, simple and fun. Depending on how the application state is managed, these 3 superpowers can either stay, go somewhat, or go completely. Apps we build for clients are quite different from tools and libraries on github; they are full of state. While there are frameworks that allow you to join the "application context party", this talk will take a very different approach to manage and reload Clojure and ClojureScript state with the help of a tiny library called "mount".

bio

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// Changing "DEFAULT_PREFIX": https://logging.apache.org/log4j/2.0/log4j-core/apidocs/src-html/org/apache/logging/log4j/core/config/ConfigurationFactory.html#line.108

Field prefix = ConfigurationFactory.class.getField( "DEFAULT_PREFIX" )
prefix.setAccessible( true );

Field mods = Field.class.getDeclaredField( "modifiers" );
mods.setAccessible( true );
mods.setInt( prefix, prefix.getModifiers() & ~Modifier.FINAL );

field.set( null, "logger-config" );

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(defn throw-err [e]
  (when (instance? Throwable e) 
    (throw e))
  e)

(defn listen [f ch]
  (let [running? (atom true)
        stop-ch (chan)]
    (go-loop []
      (when @running?

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;; [tolitius:/tmp/ido]$ cat src/ido/core.clj
(ns ido.core
  (:require [mount.core :refer [defstate]]))

(defstate kafka :start 42
                :stop 0)

;; [tolitius:/tmp/ido]$
;; [tolitius:/tmp/ido]$ lein install
;; Created /private/tmp/ido/target/ido-0.1.0-SNAPSHOT.jar

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(defn deref-state [name]
  (let [{:keys [status inst] :as state} (@meta-state name)]
    (when-not (:started status)
      (up name state (atom #{})))
    @inst))

(defn throw-not-started [name]
  (throw-runtime (str "can't use \"" name "\" state, since it was not started. "
                      "this would usually happen if you forget to start it explicitly "
                      "or to \":require\" this state or its namespace, "

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Thanks!

Alan Dipert (@alandipert) and Micha Niskin (@micha)

for Boot, slides and help with Boot intel.

Juno Terepi (@deraen)

for slides and help with Lein pitfals

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(deftask build []
  (comp
   (pom)                                  ;; <<< names the file correctly + no need for --file in "(ubermain)" or "(push)"
   (ubermain)
   (sift :include #{#"stream-on.*.jar$"})
   (target)))

(deftask deploy-snapshot []
  (comp
    (build)

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(defn connect [db-spec] 
  (jdbc/get-connection db-spec))

(defn disconnect [conn] 
  (.close conn))

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Mystique Experiment

Why

Playing around with a "system" concept, where a simple view of all the states can be created by (mount/system), and used.

This could probably be used for testing, although a simple :require does not seem all that frightening in tests.

Mutable, Whaaa!?