In Clojure, the most basic tool we have for the flow control is the
operator. It allows you to choose between two options depending upon a condition.
(def condition true) (if condition (str "evaluate first expression if true") (str "evaluate second expression if false"))
If your age is less than the legal drinking age, then you can only be served water or soda.
If your age is greater, then you have a wider set of drinks available.
(def age 24) (def legal-drinking-age 21) (if (< age legal-drinking-age) ["water" "soda"] ["water" "soda" "beer" "wine"])