UTop create_implicits not working with Emacs?

ysalmon · January 23, 2023, 5:48pm

I just discovered that one can say UTop.set_create_implicits true to have utop bind results to variables _1, _2 etc. This works well when running utop in a terminal but seems not to when running it from Emacs (ie. with the -emacs command line option) : results still get a - in front of them and no _%i variable seem to exist.

How come ?

Gopiandcode · January 24, 2023, 3:58am

I think the reason is that the uTop implementation for Emacs is missing the code to bind implicits, which seems to be a bug?:

See the code to rewrite toplevel expressions in the normal uTop loop:

github.com

ocaml-community/utop/blob/master/src/lib/uTop_main.ml#L858


      
                        return None)
                (fun () -> LTerm.flush term)
            )
          in
          match phrase_opt with
            | Some phrase ->
                (* Rewrite toplevel expressions. *)
                let count = S.value UTop_private.count in
                let phrase = rewrite phrase in
                let phrase =
                  if UTop.get_create_implicits () then
                    let binding_name = Printf.sprintf "_%d" count in
                    bind_expressions binding_name phrase
                  else
                    phrase
                in
                (* Set the margin of standard formatters. *)
                UTop_private.set_margin Format.std_formatter;
                UTop_private.set_margin Format.err_formatter;
                (* Formatter to get the output phrase. *)
                let buffer = Buffer.create 1024 in

and the corresponding code in the module implementing Emacs support:

github.com

ocaml-community/utop/blob/595002e6f07e6a3c6abc6e94a1b2448006115f1b/src/lib/uTop_main.ml#L1078


      
                | Some ("end", _) ->
                    Buffer.contents buf
                | Some (command, argument) ->
                    Printf.ksprintf (send "stderr") "'data' or 'end' command expected, got %S!" command;
                    exit 1
            in
            loop true
          
          
let process_checked_phrase phrase =
            (* Rewrite toplevel expressions. *)
            let phrase = rewrite phrase in
            try
              Env.reset_cache_toplevel ();
              ignore (execute_phrase true Format.std_formatter phrase);
              true
            with exn ->
              (* The only possible errors are directive errors. *)
              let msg = UTop.get_message Errors.report_error exn in
              (* Skip the dumb location. *)
              let msg =
                try

Maybe there’s a reason for this discrepancy? Not sure.

ysalmon · January 24, 2023, 8:24am

Thank you. I saw the first snippet by searching for implicits, but I did not realise that the emacs mode would use a different function.

So an issue to Utop it is.

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UTop create_implicits not working with Emacs?

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