Can't build a jar using Leiningen

Question

I'm trying to make a stand alone jar from my bare-bones Clojure project using the Leiningen plugin in Intellij's Cursive.

To create the project, I just created the project.clj file, opened it, and Cursive offered to import it as a project.

project.clj:

(defproject WaterTimer "1"
  :description "A timer that reminds you to drink water"
  :main tone-producer/main)

tone-producer.clj:

(ns tone-producer
  (:require [general-helpers :as g])

  (:import [javax.sound.midi MidiSystem
                             Synthesizer
                             MidiChannel])
  (:gen-class))

(defn main [& args]
  (println "Test!"))

When I run the "uberjar" task, I get the following output:

Warning: specified :main without including it in :aot. Implicit AOT of :main will be removed in Leiningen 3.0.0. If you only need AOT for your uberjar, consider adding :aot :all into your :uberjar profile instead. Warning: The Main-Class specified does not exist within the jar. It may not be executable as expected. A gen-class directive may be missing in the namespace which contains the main method. Created C:\Users\slomi\IdeaProjects\WaterTimer\target\WaterTimer-1.jar Created C:\Users\slomi\IdeaProjects\WaterTimer\target\WaterTimer-1-standalone.jar

I also tried changing the main function to have the default name, and omit the name from the defproject:

(defproject WaterTimer "1"
  :description "A timer that reminds you to drink water"
  :main tone-producer)

(ns tone-producer
      (:require [general-helpers :as g])

      (:import [javax.sound.midi MidiSystem
                                 Synthesizer
                                 MidiChannel])
      (:gen-class))

    (defn -main [& args]
      (println "Test!"))

But now I get the error:

Error: Could not find or load main class clojure.main Compilation failed: Subprocess failed

The structure is:

• WaterTimer
  • src
    • tone-producer.clj
  • project.clj
  • target

Any guidance here would be appreciated.

Answer 1

For creating uberjars, the project file should have the :aot keyword enabling ahead of time compilation.

Here is an output from my project.clj file.

(defproject jdbc "0.1.0-SNAPSHOT"
  :description "JDBC Project"
  :url "http://example.com/FIXME"
  :license {:name "Eclipse Public License"
            :url "http://www.eclipse.org/legal/epl-v10.html"}
  :dependencies [[org.clojure/clojure "1.8.0"]
                 [org.clojure/java.jdbc "0.6.1"]
                 [postgresql "9.3-1102.jdbc41"]
                 [com.mchange/c3p0 "0.9.5.2"]
                 [byte-streams "0.2.2"]]
  :main jdbc.core
  :aot [jdbc.core])

Note the :main and :aot entries. Also it needs to be -main as already stated by birdspider.

Answer 2

After a bit of fiddling

• I dropped (:require [general-helpers :as g]) since its not necessary to demostrate the issue
• Error: Could not find or load main class clojure.main Compilation failed
  • you didn't include the clojure dependency [1]
• :gen-class needs AOT - as Sanchayan pointed out
  • see [2]

project.clj

(defproject WaterTimer "0.0.1"
  :description "A timer that reminds you to drink water"
  :dependencies [[org.clojure/clojure "1.8.0"]] ;; <- [1]
  :main tone-producer    
  :aot [tone-producer])  ;; <- [2]

src/tone_producer.clj - USE '_' instead of '-' in the filename

(ns tone-producer
  (:import [javax.sound.midi MidiSystem
                             Synthesizer
                             MidiChannel])
  (:gen-class))

(defn -main [& args]
  (println "Test!"))

Result:

$ lein uberjar
Compiling tone-producer
Compiling tone-producer
Created .../watertimer/target/WaterTimer-0.0.1.jar
Created .../watertimer/target/WaterTimer-0.0.1-standalone.jar
$ java -jar target/WaterTimer-0.0.1-standalone.jar 
Test!

---

Generally I'd recommend to init a project with lein new <name> via command line and the import it into Cursive/Other IDE of choice.