core.typed is an optional static type system for Clojure, providing gradual typing features like type declarations, checking, and inference. It supports modules for development-time checking and runtime typing, though note that it's deprecated as of Clojure 1.11 in favor of Typed Clojure. core.typed is separated into modules. You'll want the full type checker at development time, and the runtime dependencies in production. Then, lein repl will automatically activate the :dev profile. Verify the type checker is not included in uberjars with lein with-profile uberjar deps :tree.