Add initial elixir-ls support

[viniciusmuller]

Due to the way that elixir-ls works in nvim-lspconfig, I could not set cmd on the file, so the installation is currently working and the user needs to set elixirls's cmd as /home/<user>/.local/share/nvim/lspinstall/elixir/language_server.sh on setup in order to the language server to start. I wonder if we can improve this and make it work out of the box or just add documentation about that issue.

[kabouzeid]

Just add config.default_config.cmd = { "./language_server.sh" }

[viniciusmuller]

I was getting some strange errors with the :LspInstall command completion before when tried with that line, but now it seems to be working

[kabouzeid]

Perhaps you were missing the { } before?

[viniciusmuller]

I tried the first time just indexing the cmd field and setting a string value, but it didn't existed, so I also tried to create it before doing that, (which is the same as the line you sent) and both don't cause errors but the lsp doesn't seem to start.
It has started before because I've forgot that I had hardcoded the path in my vimrc's elixirls setup for testing.

[kabouzeid]

what does :LspInfo say?

[viniciusmuller]

Configured servers: elixirls
Neovim logs at: /home/<user>/.cache/nvim/lsp.log

0 client(s) attached to this buffer: 

0 active client(s): 

Clients that match the filetype elixir:
  
  Config: elixirls
  	cmd:               cmd not defined
  	cmd is executable: cmd not defined
  	identified root:   /home/<user>
  	custom handlers:   

[viniciusmuller]

I'll commit the current code

[kabouzeid]

Needs to be ./elixir-ls/language_server.sh. The ./ is important to be recognized as a local path.

[viniciusmuller]

Oh yes, I forgot the ./, but even adding it the behaviour and :LspInfo output are still the same.

[kabouzeid]

That's very weird. I suspect something in your config is wrong because the code looks fine. Also I just tested it, and it works on my machine.

[kabouzeid]

Looks good, only thing is I would prefer it if you would extract the .zip file into a subdirectory elixr-ls. Then use rm -rf elixir-ls before unzipping. This ensures it can be cleanly reinstalled without causing any issues because of existing files during unzipping.

Something like this pseudo code

rm -rf elixr-ls
curl 
unzip zip to elixr-ls
chmod
rm zip

[kabouzeid]

Thanks!

[qgadrian]

Just for reference, I had problems with elixir-ls not working correctly in my machine (local modules not recognized, for example).

After finding this issue in their repo I manually checked out the project and built it with my local Elixir, and everything started working perfectly again.

I believe nvim-lspinstall for this matter shouldn't use the release zip provided by elixir-ls and compile the project instead, using the Erlang version installed in the system. @kabouzeid I will prepare a PR to compile elixir-ls and just not extract a zip when is installed by nvim-lspinstall.