Something that has me stumped. A NS with a :gen-class directive and a main. The first version of main doesn't work (it never seems to execute the for loop). The second one works. What am I missing?

gistfile1.clj

;;; Some NS which has the gen-class directive

(defn -main-that-wont-work []
  (let [coll (some-collection-returning-function)]
    (for [c coll]
      (transform c)
    )
  )
)

;;; Take 2

(defn -main-that-works []
  (let [coll (some-collection-returning-function)
        transformed (map transform coll)]
      ;;; nothing to do
      transformed
  )
)