Allow setting line width for refmt

[rusty-key]

There is currently no way of setting up line width for refmt other than passing flag to the command.

While we at this point, I am suggesting to introduce --refmt-width argument to ocamllsp and pass it to refmt. On editor extension side a setting for refmt can be introduced and passed to ocamllsp instance: ocamllabs/vscode-ocaml-platform#184

Related issue in reason repo: reasonml/reason#2567

[giltho]

Hey !
Following up on and summarizing what has been said in ocamllabs/vscode-ocaml-platform#184:
-> passing the option to the ocamllsp command line arguments is not the right way to do things

-> The best way is to pass the argument to the formatting options because it is what is intended to. However, in our case it might be a tiny bitsy more difficult to implement given that the FormattingOption type is generated and custom fields are not handled right now. The type generator could be extended with a mechanism that adds a custom_ field of type

[> `String of string, `Bool of boolean, `Int of int, `Float of float]

for this [key: string]: boolean | number | string
Once that is done the implementation is trivial both here and in the vscode extension.

-> The 2nd best way is to use workspace configuration. But then you would need to implement the whole configuration system which is probably even more trouble.

So I have not said anything new from what has already been said in the discussion on your vscode-ocaml-platform PR apart from implementation details. Feel free to ping if you need any help.

[rusty-key]

Hey @giltho! Thanks for the summary. The part I am struggling with is actually on the client side: I cannot understand when and how to pass DocumentFormattingParams from the client. Looking at spec I thought that I need to register it via ClientCapabilities during initialization, but it looks like that's not what you are talking about. Can you direct me in the right direction?

[giltho]

Ah damn... Took me a while to find it: https://github.com/microsoft/vscode-languageserver-node/blob/363e9228a87d3df51427474ecc596740c3fecfd5/client/src/codeConverter.ts#L616

The params sent by the vscode client are hardcoded... Language clients like Typescript's for VSCode are custom-written, and are not using the high-level LanguageClient class, so that's why they can use additional parameters...

So the first possiblity would be to fix the vscode-language client, but that's very much annoying, because we'd have to wait on the next vscode update....

I guess you should go with the workspace configuration option

[rgrinberg]

@giltho is right. Let us know when this PR is updated and is ready for review again.

[rusty-key]

@rgrinberg, I'll have some time over this weekend to refactor the PR

[rgrinberg]

Please re-open when that weekend comes. Note that master already has the infrastructure for maintaining a Configuration.t value. So implementing this feature should be quite easy.