What I would like to do is trace the function aux that has restricted scope in a definition like:
let example = function
arg ->
let rec aux =
(* some recursive function body*)
in
aux arg
;;
with #trace or a similar toplevel command, so that the trace appears when example is called.
(without just copy-pasting the auxiliary function under some other name and passing it to the toplevel)
note: I am using tuareg mode on emacs
No. In the toplevel, you can trace only toplevel functions.