Function clojure_loop_prompt 

pub fn clojure_loop_prompt<F>(cx: &mut Cx, input: Ref, body: F) -> Result<Ref>
where
    F: FnOnce(&mut Cx) -> Result<Ref>,

Runs body inside the Clojure loop prompt so a nested clojure_recur can rebind it.

Maps the surface loop form onto a kernel control prompt; behavior lives in the control organ, not this profile.