Metals: Add installation instructions for Emacs

[olafurpg]

I would love to update the website to document the installation instructions for Emacs using lsp-scala (https://github.com/rossabaker/lsp-scala/). I've been planning to do this for awhile but I have limited experience with Emacs so I got stuck on my first attempt and never got around to finish it.

cc/ @rossabaker

[olafurpg]

Would someone be able to help out with this? I've spent a couple hours trying to get lsp-scala working on my computer but I've never used Emacs before so it's all new to me.

• docs on updating Metals website https://scalameta.org/metals/docs/contributors/updating-website.html
• it would be great to have a screenshot/gif of Metals running inside Emacs
• we can use vim.md as a base template
• lsp-scala instructions: https://github.com/rossabaker/lsp-scala/

The benefit of documenting the Emacs installation on the Metals website is that version numbers for generating the metals-emacs binary will stay up-to-date as new releases are published.

[olafurpg]

cc/ @coreyoconnor

[olafurpg]

Alternatively, if someone can give me a pointers on how to get started from a completely clean ~/.emacs.d then I'd love to give it another try myself. I struggled most with installing packages.

[fommil]

I wrote extensive Learning Emacs docs over at

• http://ensime.github.io/editors/emacs/learning/
• http://ensime.github.io/editors/emacs/hacks/

that you may wish to use for your own benefit.

[olafurpg]

@fommil thanks, I got it working!

[olafurpg]

Whoops, fat thumb closed the issue while I was writing a response.

[rossabaker]

It's a little more burdensome than it ought to be because the package isn't in MELPA yet, like its dependency. I did some of the ceremonial linting to get it up to standard. I'll try to submit it to MELPA today.

[olafurpg]

I like how Emacs highlights the line that you navigate to

I'll open a PR soon updating the docs. The integration is not perfect yet, I can't get lsp-mode to send the correct shutdown and exit hooks. It also sends textDocument/hover requests even if Metals does not declare a hover provider. Those can be improved on in the future.

[olafurpg]

@rossabaker would it be possible to enable the hook by default?

(add-hook 'scala-mode-hook #'lsp-scala-enable)

I'm not aware of another editor that require enabling the language server on a file-basis. It's more common to disable/enable the LSP package on per-project.

[fommil]

@rossabaker what do you mean "like its dependency"? https://melpa.org/#/lsp-mode

[fommil]

@olafurpg btw, just so you know, the red squiggly support is already provided, (non-ensime) emacs by sbt's lsp and/or flycheck. I suspect the docs may need to touch on disabling things or everybody is going to get conflicts and perf regressions. Spacemacs often enables stuff by default.

[gabro]

That's a very good point, We do the same for VSCode's docs, for other available Scala LSP extensions, so it makes sense for Emacs too.