;; I've called this function "my-inc" so you don't confuse it with inc.
;; inc is a built-in function that already does this for us.
(defn my-inc [n] (+ 1 n))

(println (my-inc 5))

(def my-inc-2 (fn [n] (+ 1 n)))

(println (my-inc-2 5))

(println ((fn [n] (+ 1 n)) 5))

(println (#(+ 1 %) 5))

(println (#(str %1 %2 %3) "foo" "bar" "baz"))