Feature request: Update default profile to use indicate-multiline-delimiters = closing-on-separate-line

[hcarty]

Is your feature request related to a problem? Please describe.

The indicate-multiline-delimiters = closing-on-separate-line setting was deprecated in ocamlformat 0.20.0. I've personally found this feature very useful and had good feedback from other developers on the same codebase after it was introduced. In particular, it makes modifying anything with a closing delimiter easier because the last line of the delimited body is no longer special. This also makes diffs easier to understand as the )/]/} no longer clutters diffs when the delimited body changes.

Describe the solution you'd like

I would like to have indicate-multiline-delimiters = closing-on-separate-line as part of the default profile. As @gpetiot pointed out to me, this will cause a lot of churn for users of the default profile! So this seems like it's worth considering before a 1.0.0 release.

Additional context

Issues:

• Existing request for closing parens on a separate line: Feature request: trailing parentheses on new line #1578
• Other issues mentioning this feature which may indicate interest in it - leaving out my own to avoid too much bias!:
  • Bug: trailing whitespace produced with indicate-multiline-delimiters=closing-on-separate-line #1762
  • Bug: Invalid syntax generation when file that uses "let open ... in" is formatted with --indicate-multiline-delimiters=closing-on-separate-line #1596
  • bad indentation with indicate-multiline-delimiters=closing-on-separate-line #927

PRs:

• Deprecation of the feature: Deprecate value 'closing-on-separate-line' for option 'indicate-multiline-delimiters' #1900
• Original implementation: Improve: add a new way to indicate multiline delimiters #876

[hcarty]

A gentle ping - is there any chance of this happening? At work we've been sticking with 0.19.0 in large part because of this deprecation and I've done the same with personal projects.

[gpetiot]

Hi, sorry for the late reply.

I don't know if this option will be part of the default profile, this profile is driven by the maintainers of the mirage and the ocaml platform projects. @samoht @tmattio what do you think of having this setting by default?

For the record I like this option as well, in other issues I mentioned that I would like to put together a profile that would be more diff-friendly than the default one, that would vertically unfold most of the code (kinda like the deprecated sparse profile without the unnecessary line breaks). And such profile would use this setting.
Most deprecated options won't disappear overnight, my plan is to have most users happy with the available profiles before removing the options, so you can safely use them in the meantime.

[hcarty]

Thank you @gpetiot - I've seen your comments about wanting a more diff-friendly format and I agree!

Would it be more helpful for me to reframe this issue as a request for a more diff-friendly or newcomer friendly version of the default profile? I could also open a new issue for that purpose. I don't want to add issue noise though if that wouldn't be helpful for you.

[gpetiot]

Would it be more helpful for me to reframe this issue as a request for a more diff-friendly or newcomer friendly version of the default profile? I could also open a new issue for that purpose. I don't want to add issue noise though if that wouldn't be helpful for you.

I don't think it's necessary to open an issue, I will get working on it soon and you can give feedback once the PR is open.

[hcarty]

Sounds good - thank you!

[gpetiot]

I opened #2020, don't hesitate to give some feedback if you have time to give it a try!

[hcarty]

Thank you! I'll give it a try this week or next.

[tmattio]

I just tried the diff-friendly profile and left some feedback on the PR.

I don't know if this option will be part of the default profile, this profile is driven by the maintainers of the mirage and the ocaml platform projects. @samoht @tmattio what do you think of having this setting by default?

IMHO, it's a good idea to have a default profile that is driven independently of any project or preference. I could definitely see this diff-friendly profile becoming the default and creating a mirage profile from the current default one.