Unless you use Typed Clojure, which is a library. https://github.com/typedclojure/typedclojure https://github.com/typedclojure/typedclojure I haven't used it,

Unless you use Typed Clojure, which is a library. https://github.com/typedclojure/typedclojure https://github.com/typedclojure/typedclojure I haven't used it, so I don't know its tradeoffs; but its docs say its types exist at compile time: https://github.com/clojure/core.typed/wiki/User-Guide https://github.com/clojure/core.typed/wiki/User-Guide