declare

(declare name...)

Forward-declares each name: the pass one pre-scan collects every declare name alongside the top-level def/defn names, so a definition above may call a function only defined below it. A real definition wins over a declaration. A declared-but-never-defined name is an unbound var, like the oracle's: its value and @#'name are the unbound root (truthy; str gives Unbound: #'user/name; it prints #<Unbound: #'user/name>), calling it signals Attempting to call unbound fn: #'user/name, and bound? is false. A declare leaves a bound root alone and adds :declared true to the var's metadata; a ^:dynamic name rebinds with binding. The form itself answers nil.