Stream expression and compile

Hi there,
From https://ocaml.org/learn/tutorials/stream_expressions.html I
created a file walk.ml containing the following:

let rec walk dir =
    let items =
      try
        Array.map
          (fun fn ->
             let path = Filename.concat dir fn in
             try
               if Sys.is_directory path then `Dir path
               else `File path
             with e -> `Error (path, e))
          (Sys.readdir dir)
      with e -> [| `Error (dir, e) |] in
    Array.fold_right
      (fun item rest ->
         match item with
         | `Dir path -> [< 'item; walk path; rest >]
         | _ -> [< 'item; rest >])
      items
      [< >];;


let () =
    Stream.iter
      (function
       | `Dir path ->  Printf.printf "dir: %s%!\n" path
       | `File path -> Printf.printf "file: %s%!\n" path
       | `Error (path, e) ->
           Printf.printf "error: %s (%s)%!\n" path
             (Printexc.to_string e))
      (walk "/tmp");;


Running this in utop works fine when I did
#use "topfind";;
#camlp4o;;

before.


However, I have no idea how to create a bytecode or native executable
from above code. 

If this is dead simple I would like to get a pointer to the
documentation so that I learn what I missed to read.


Any help appreciated.  Thanks.


-- 
Manfred