Clojure Newbie - Namespace troubles

I'm learning Clojure and so far I can't make sense of this little conundrum which I'm sure is ridiculously basic. I have this file : ``` (ns cloapp.core (:gen-class)) (defn -main "I don't do a whole lot ... yet." [& args] (println "Hello, World!") (println "Well Hi there, im a string !") (println "Why wont this work !") (myFunc "Hiya")) (defn myFunc [aVar] (println aVar)) ``` If I try and run this with, ``` lein run ``` It complains and says, ``` Caused by: java.lang.RuntimeException: Unable to resolve symbol: myFunc in this context ``` But if I remove the call to myFunc from main and do, ``` lein repl cloapp.core=> (myFunc "Hiya !") Hiya ! nil cloapp.core=> ``` Then I can call it. Why is this ? I'm assuming it's something to do with the namespace but reading up on it I can't work it out. A