Playing around with Neovim 0.5 LSP and fsharp-language-server

[PhilT]

FYI, I've been messing around trying to get Neovim nightly's LSP working with fsharp-language-server and I'm happy to report that with some tweaking (https://github.com/neovim/neovim/pull/13001) it works! I get completion, errors, symbols, etc.

[jubnzv]

@PhilT Hi, I'm trying to use fsharp-language-server with nvim-lsp too, but not sure, why it doesn't work.

Could you share your configuration, please?

I created the following configuration, which seems correct for me:

local configs = require 'nvim_lsp/configs'
local util = require 'nvim_lsp/util'

configs.fsharp_language_server = {
  default_config = {
    -- Path to binary created with `dotnet publish -c Release -r linux-x64 src/FSharpLanguageServer`.
    -- I also tried to use cmd for `dotnet exec $path/FSharpLanguageServer.dll`.
    -- Both solutions work well from the command line.
    cmd = {"/home/jubnzv/Sources/fsharp-language-server/src/FSharpLanguageServer/bin/Release/netcoreapp3.0/FSharpLanguageServer",};
    filetypes = {'fsharp',};
    root_dir = util.root_pattern(".git");
  };
  docs = {
    description = [[
https://github.com/fsprojects/fsharp-language-server

This project is an implementation of the language server protocol using the F# Compiler Service.
    ]];
    default_config = {
      root_dir = [[root_pattern(".git")]];
    };
  };
}

This is somewhat strange, since I don't get any errors in lsp logs and I also can execute fsharp-language server directly.

[PhilT]

You'll need the code from the PR that I raised above (https://github.com/neovim/neovim/pull/13001).

Here is Lua config in init.vim

:lua << END
local nvim_lsp = require 'nvim_lsp'
local configs = require 'nvim_lsp/configs'

configs.fsharp = {
  default_config = {
    cmd = {"dotnet", "/home/phil/code/fsharp-language-server/src/FSharpLanguageServer/bin/Release/netcoreapp3.1/FSharpLanguageServer.dll"};
    filetypes = {"fsharp"};
    root_dir = nvim_lsp.util.root_pattern("*.fsproj", ".git");
  };
}

local nvim_command = vim.api.nvim_command
local on_attach = function(client, bufnr)
  require'completion'.on_attach{}
  require'diagnostic'.on_attach{}
  nvim_command('autocmd CursorHold <buffer> lua vim.lsp.util.show_line_diagnostics()')
end

nvim_lsp.fsharp.setup{on_attach = on_attach}
nvim_lsp.tsserver.setup{}
END

Shout if you need some more direction on setting it up.

Cheers, Phil

[jubnzv]

@PhilT It started working after applying your patch.

Thank you very much! :)

[PhilT]

@jubnzv Commit https://github.com/neovim/neovim/pull/13174 means the patch is no longer required and works with the latest Neovim 0.5 master.

[jubnzv]

@PhilT Thanks, yes, it works. There are some problems with nvim-lsp in neovim's HEAD (https://github.com/neovim/neovim/issues/13210), but earlier versions works well with fsharp-lsp-server.