[Caml-list] What is the right way to configure Tuareg to get the same indentation as in Batteries Included?

[Caml-list] What is the right way to configure Tuareg to get the same indentation as in Batteries Included?

[Matej Košík]

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Hi,

Tuareg and indentation does not work for me very well.

I am trying to figure out how should I configure it so that I get the same indentation behavior as is used in Batteries Included.

One (of several) problem is with the or-patterns in match-expressions.

Here is the original sample:
(behavior I like)

  (* https://github.com/ocaml-batteries-team/batteries-included/blob/e069e28678a0d15d338721e1ff5e480fe0ad26c5/src/batComplex.ml#L82-L83 *)

  match BatEnum.peek enum with
  | None -> {re; im = multiplier}
  | Some (Kwd ".")
  | Some (Kwd "*") ->
    BatEnum.junk enum;
    parse_im ~multiplier re
  | Some _token ->
    parse_im ~multiplier re

However, Tuareg, in my currenct configuration does instead this:

  match BatEnum.peek enum with
  | None -> {re; im = multiplier}
  | Some (Kwd ".")
    | Some (Kwd "*") ->
     BatEnum.junk enum;
     parse_im ~multiplier re
  | Some _token ->
     parse_im ~multiplier re

I am using:
- Ocaml 4.06.0+beta2
- Tuareg 2.0.10 (installed via OPAM)
and my ~/.emacs file contains just this:

  (load "~/.opam/4.06.0+beta2/share/emacs/site-lisp/tuareg-site-file")
  (setq tuareg-indent-align-with-first-arg t)
  (setq tuareg-match-patterns-aligned t)

which is, I guess, wrong/insufficient.

I'd be grateful for any hints concerning how to fix/complete the configuration in order to get indentation behavior consistent with Ocaml Batteries.
Is that possible (with Tuareg or whatever other tool)?

---

Matej


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Re: [Caml-list] What is the right way to configure Tuareg to get the same indentation as in Batteries Included?

[Stefan Monnier]

>   match BatEnum.peek enum with
>   | None -> {re; im = multiplier}
>   | Some (Kwd ".")
>   | Some (Kwd "*") ->
>     BatEnum.junk enum;
>     parse_im ~multiplier re
>   | Some _token ->
>     parse_im ~multiplier re
>
> However, Tuareg, in my currenct configuration does instead this:
>
>   match BatEnum.peek enum with
>   | None -> {re; im = multiplier}
>   | Some (Kwd ".")
>     | Some (Kwd "*") ->
>      BatEnum.junk enum;
>      parse_im ~multiplier re
>   | Some _token ->
>      parse_im ~multiplier re

Here's how you can do it:
- Go to the first line that Tuareg indents wrong (i.e. `| Some (Kwd "*") ->`)
- Change its indentation to match your expectation
- run `M-x smie-config-set-indent RET`
- this should suggest to set (:before "|-or") to 0, which you can accept.
- go to the next line (that Tuareg indents wrong)
- Change its indentation to match your expectation
- run `M-x smie-config-set-indent RET`
- this time it asks you which rule you want to change (because 2 rules
  are used to determine this indentation): either (after "->") or
  (before "->") depending on whether you want to also change

     | Some (Kwd "*")
       -> BatEnum.junk enum;

  or not.

- once that is done, you should be able to do `M-x smie-config-save
  RET`.  To save the result into your Customize settings.


        Stefan

Re: [Caml-list] What is the right way to configure Tuareg to get the same indentation as in Batteries Included?

[Matej Košík]

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Hi Stefan,

On 11/21/17 20:59, Stefan Monnier wrote:
>>   match BatEnum.peek enum with
>>   | None -> {re; im = multiplier}
>>   | Some (Kwd ".")
>>   | Some (Kwd "*") ->
>>     BatEnum.junk enum;
>>     parse_im ~multiplier re
>>   | Some _token ->
>>     parse_im ~multiplier re
>>
>> However, Tuareg, in my currenct configuration does instead this:
>>
>>   match BatEnum.peek enum with
>>   | None -> {re; im = multiplier}
>>   | Some (Kwd ".")
>>     | Some (Kwd "*") ->
>>      BatEnum.junk enum;
>>      parse_im ~multiplier re
>>   | Some _token ->
>>      parse_im ~multiplier re
> 
> Here's how you can do it:
> - Go to the first line that Tuareg indents wrong (i.e. `| Some (Kwd "*") ->`)
> - Change its indentation to match your expectation
> - run `M-x smie-config-set-indent RET`
> - this should suggest to set (:before "|-or") to 0, which you can accept.
> - go to the next line (that Tuareg indents wrong)
> - Change its indentation to match your expectation
> - run `M-x smie-config-set-indent RET`
> - this time it asks you which rule you want to change (because 2 rules
>   are used to determine this indentation): either (after "->") or
>   (before "->") depending on whether you want to also change
> 
>      | Some (Kwd "*")
>        -> BatEnum.junk enum;
> 
>   or not.
> 
> - once that is done, you should be able to do `M-x smie-config-save
>   RET`.  To save the result into your Customize settings.

So far so good.
After following the above instructions, I was able to tweak the Emacs behavior in the desired way.
Thank you!

What puzzled me was that once I restart Eamcs, I get the old behavior.

I am guessing that this is because I need to "save" the configuration somehow, which I failed to figure out.

So, first, one must "save SMIE configuration" to "customize setting".

And then one must "save customize settings" to ~/.emacs

QUESTION: Is that right?

MY ASSUMPTION WAS: Yes.

I have tried two things (and I failed in both cases);

the 1-st attempt:
-----------------

  After doing "M-x smie-config-save", I have tried to use "M-x customize-save-variable smie-config".
  Emacs responded:

    Wrote /home/mkosik/.emacs

  This sounded like a progress.

  After I looked at ~/.emacs, I can see this:

    (load "/home/mkosik/.opam/4.06.0/share/emacs/site-lisp/tuareg-site-file")
    (custom-set-variables
     ;; custom-set-variables was added by Custom.
     ;; If you edit it by hand, you could mess it up, so be careful.
     ;; Your init file should contain only one such instance.
     ;; If there is more than one, they won't work right.
     '(inhibit-startup-screen t)
     '(smie-config nil))
    (custom-set-faces
     ;; custom-set-faces was added by Custom.
     ;; If you edit it by hand, you could mess it up, so be careful.
     ;; Your init file should contain only one such instance.
     ;; If there is more than one, they won't work right.
     )

  This does not seem currect, does it?
  (At least I would expect "smie-config" variable to be set to something interesting, not "nil".)

  To confirm, I restarted Emacs and I can confirm, that the Emacs behaves again in the original undesired way
  (defined in my first email)

  FAIL

the 2-nd attempt

  After repreating your helpful instructions and doing "M-x smie-config-save",
  I tried to use "M-x customize-save-customized"
  Emacs responded:

    Wrote /home/mkosik/.emacs

  That file changed in the following way:

    (load "/home/mkosik/.opam/4.06.0/share/emacs/site-lisp/tuareg-site-file")
    (custom-set-variables
     ;; custom-set-variables was added by Custom.
     ;; If you edit it by hand, you could mess it up, so be careful.
     ;; Your init file should contain only one such instance.
     ;; If there is more than one, they won't work right.
     '(inhibit-startup-screen t)
     '(smie-config
       (quote
        ((tuareg-mode
          (2 :after "->" 1)
          (0 :before "|-or" nil))))))
    (custom-set-faces
     ;; custom-set-faces was added by Custom.
     ;; If you edit it by hand, you could mess it up, so be careful.
     ;; Your init file should contain only one such instance.
     ;; If there is more than one, they won't work right.
     )

  This is more like it (I thought).
  I optimistically restarted Emacs and again, unfortunatelly, Emacs behaves again in the original undesired way
  (defined in my first email).
  I find this strange because "M: (print smie-config)" gives me:

    (tuareg-mode (2 :after "->" 1) (0 :before "|-or" nil)))
    (tuareg-mode (2 :after "->" 1) (0 :before "|-or" nil)))

  FAIL

Is this a bug?
Is this the expected behavior and I merely do not understadn SMIE and should read some more documentation? If yes, then which one?

I haven't noticed many questions about Ocaml indentation in Emacs, so I am guessing that this works for everyone perfectly.
Is that the case?


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Re: [Caml-list] What is the right way to configure Tuareg to get the same indentation as in Batteries Included?

[Stefan Monnier]

> After following the above instructions, I was able to tweak the Emacs
> behavior in the desired way.
> Thank you!
> What puzzled me was that once I restart Eamcs, I get the old behavior.

Turned out it was a bug in the smie-config code.  This is fixed in
Emacs-26.


        Stefan