Add completion-at-point implementation ocaml-community/utop#261

[j-shilling]

After poking around for ways to use my normal completion-at-point workflow in the utop buffer, I came accross issue #261, which is a feature request to provide a completion-at-point-fuction.

This is an implementation I came up with that works for me and I wanted to share it here in case anyone else found it useful or had any feedback.

[rgrinberg]

@bbatsov could you review?

[bbatsov]

Overall the code looks good to me. In general I think this should be enabled by default - probably unconditionally, given it's the more generic method of completion in Emacs. I see very little point to have to enable manually a capf function. Given how basic the company-backend is, probably at some point it can go away, as company has a capf backend anyways.

[bbatsov]

While you're at this - I'd also suggest incorporating those doc improvements proposed a while ago #326

[j-shilling]

Overall the code looks good to me. In general I think this should be enabled by default - probably unconditionally, given it's the more generic method of completion in Emacs. I see very little point to have to enable manually a capf function. Given how basic the company-backend is, probably at some point it can go away, as company has a capf backend anyways.

As a temporary fix, I added a dispatch function that can be bound to TAB that either calls completion-at-point or starts the company workflow. I haven't used company in a long time, but is there any more to this than just removing the current backend and adding company-capf backend instead in utop-mode?

If it's that simple, I can do that here and then merge in #326 with changes that explain which backend to use. It might also be worth removing the complete command and renaming company-complete along with removing the complete-word response. I'm very new to OCAML, so I might not be the right guy to do that.

[bbatsov]

I haven't used company in a long time, but is there any more to this than just removing the current backend and adding company-capf backend instead in utop-mode?

You don't really need to do anything in utop-mode for company-capf to work, provided it registers some completions-at-point function. The purpose of the special company backends is to provide some enhanced functionality, more metadata, etc. Obviously that wasn't the case with the existing backend, that's why I think it becomes kind of redundant.

It might also be worth removing the complete command and renaming company-complete along with removing the complete-word response.

Yeah, I'm not sure why it was made company-specific in utop itself. I guess the author of the functionality was a company user and this was before capf became popular (and company alternatives like corfu).

[bbatsov]

@rgrinberg @emillon Seems we forgot about this PR, which is good to merge IMO. (especially given that company-mode as not as popular as it used to be)

[emillon]

ok, thanks!

[bbatsov]

Thanks!