Could not locate clojure/core/async__init.class or clojure/core/async.clj on classpath

Question

Does anyone know why I'm getting the below error? I read through answers of similar questions, which recommended using Leiningen, which I've done below and still get the error.

MacBook-Pro:~ xxx$ lein new app test

Generating a project called test based on the 'app' template.

MacBook-Pro:~ xxx$ cd test
MacBook-Pro:test xxx$ lein repl
nREPL server started on port 59623 on host 127.0.0.1
REPL-y 0.2.1
Clojure 1.5.1
Docs: (doc function-name-here)
      (find-doc "part-of-name-here")
Source: (source function-name-here)
Javadoc: (javadoc java-object-or-class-here)
Exit: Control+D or (exit) or (quit)
Results: Stored in vars *1, *2, *3, an exception in *e
test.core=> (require '[clojure.core.async :as async :refer :all])
**FileNotFoundException Could not locate clojure/core/async__init.class or clojure/core/async.clj on 
classpath:   clojure.lang.RT.load (RT.java:443)**

test.core=>

---

I also tried via cider repl in emacs:

; CIDER 0.3.1 (Clojure 1.5.1, nREPL 0.2.3)
user> (require '[clojure.core.async :as async :refer :all])

FileNotFoundException Could not locate clojure/core/async__init.class or clojure/core/async.clj on classpath:   clojure.lang.RT.load (RT.java:443)

user> 

Answer 1

You need to add it to your project.clj file. See the README for details for the current version. Once you make the necessary changes to project.clj, you need to restart the repl.