Can't see printed values if launch script with `java`

问题

I have this code:

(ns test
  (:gen-class))

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

But when I run java -cp clojure-1.6.0/clojure-1.6.0.jar clojure.main test.clj I get no output. Why? How to fix this?

回答1:

Both ns and defn do not output anything. If you would like to print "hello!" by invoking the -main function, you have to add a function call at the end of the test.clj file.

(ns test
  (:gen-class))

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

(-main)

回答2:

You call the -main function like so:

java -cp clojure-1.6.0/clojure-1.6.0.jar clojure.main -i test.clj -m test

-i loads up a file

-m launches the -main function in a namespace

来源：https://stackoverflow.com/questions/30151387/cant-see-printed-values-if-launch-script-with-java