Is there any interest in supporting a HOCON formatter?

[ekrich]

The Scala version of lightbend/config (https://github.com/ekrich/sconfig) that supports JVM, Native, and JS now has some formatting support thanks to a contributor. As far as I know sconfig is a dependency so it might not be a super big deal to support.

[kastoestoramadus]

Hi it's me, the contributor ;). Plan for MVP is to provide integration with pre-commit and sbt. Later, working in JS stack. For Scala native I would need to make some research to develop formatter for it.

[tgodzik]

It's probably best to try and support it as a separate plugin to VS Code, there is nothing in Metals it needs. We would avoid some feature creep and a plugin might a cool project itself. It can be done with Scala JS easily. There is an example in https://github.com/doofin/vscode-scalajs-hello

[ekrich]

Could you explain at a high level how scalafmt works with Metals?

[tgodzik]

It's mostly done via dynamic interfaces from scalafmt used in https://github.com/scalameta/metals/blob/main/metals/src/main/scala/scala/meta/internal/metals/FormattingProvider.scala

We just invoke the formatting with the path to the config.

[ekrich]

So the format command in the IDE sends a LSP with the filename to the Metals backend and it invokes scalafmt? Does Metals register to handle .scala files on the format command? I am most familiar with VSCode.

The reason I asked this question is that I thought that sconfig was already used in Metals but I think I was confusing Metals with scalafmt.

[tgodzik]

Metals registers as an LSP server for .scala and .java extensions, so if we set the formatting capability the LSP client will send us the formatting requests.

I think we could have it as a totally separate extension at this point, since scalafmt also compile to JS from what I remember.

[ekrich]

Sure, just didn't know how that worked exactly.