Here's another example showing how you can use the :fn spec to relate the :args and :ret values in arbitrary ways. (defn title-case "Capitalizes the firs

Here's another example showing how you can use the :fn spec to relate the :args and :ret values in arbitrary ways. (defn title-case "Capitalizes the first letter of each word" [s] (str/replace s #"(\w+)" (comp str/capitalize second))) (title-case "moving pictures") ;; => "Moving Pictures" (spec/fdef title-case :args (spec/cat :s string?) :ret string? :fn #(= (-> % :args :s str/capitalize) (-> % :ret str/capitalize)))