How do I configure haskell-tools.nvim to tell haskell-language-server that my format provider is fourmolu?

[juarpr]

Hi everyone, How do I configure haskell-tools.nvim to tell haskell-language-server that my format provider is fourmolu?
If you could do it through haskell-tool.nvim instead of haskell-language-server directly, the integration with neovim would be better

[mrcjkb]

you can configure haskell-language-server by passing a Lua table via the haskell-tools config.

See :h haskell-tools.config and :h haskell-tools.lsp.ClientOpts.

[mrcjkb]

You probably don't want to create an LspAttach autocommand in ftplugin/haskell.lua.
It might get created after the LSP client attaches and thus never triggered.

[juarpr]

The :LspInfo command gets:

==============================================================================
lspconfig: require("lspconfig.health").check()

LSP configs active in this session (globally) ~
- Configured servers: lua_ls
- OK Deprecated servers: (none)

LSP configs active in this buffer (id=1) ~
- Language client log: ~/.local/state/nvim-fourm/lsp.log
- Detected filetype: `haskell`
- 1 client(s) attached to this buffer
- Client: haskell-tools.nvim (id: 1, bufnr: [1])
  filetypes:       haskell, lhaskell
  root directory:  ~/calpolifourm
  cmd:             ~/calpolifourm/haskell-language-server-wrapper --lsp --logfile /tmp/nvim-fourm.beatriz/NDDqUi/0-haskell-language-server.log
  autostart:       false

Docs for active configs: ~
- 

I don't know how to tell my autocommand that my LSP client is haskell-tools.nvim. Even when I type autocommand into init.lua I still get:

   Warn  06:37:04 notify.warn [LSP][haskell-tools.nvim] timeout
   Warn  06:37:05 notify.warn [LSP][haskell-tools.nvim] timeout
06:37:05 msg_show "~/calpolifourm/app/Main.hs" 
06:37:05 msg_show "~/calpolifourm/app/Main.hs" 1315L, 63275B

[mrcjkb]

I don't know what you're trying to do.
If you call vim.lsp.buf.format() with sync = true, it can time out, as is described in the :h vim.lsp.buf.format() documentation.
This is not specific to haskell-tools or haskell-language-server.

[juarpr]

I fixed it, thanks for the patience:

vim.keymap.set('n', '<space>f', function()
  -- With the async=false flag, the format request is guaranteed to be blocked until it is complete,
  -- so that it finishes formatting completely before emptying the file to disk.
  vim.lsp.buf.format { async = false, timeout_ms = 10000 }
end, opts)

With timeout_ms=10000, fourmolu formats it and does not issue any timeout warning

[juarpr]

With the autocommand, it formats it when saving, but issues the warning:

-- 1
vim.api.nvim_create_autocmd("LspAttach", {
  group = vim.api.nvim_create_augroup("lsp", { clear = true }),
  callback = function(args)
    -- 2
    vim.api.nvim_create_autocmd("BufWritePre", {
      -- 3
      buffer = args.buf,
      callback = function()
        -- 4 + 5
        vim.lsp.buf.format { async = false, timeout_ms = 10000, id = args.data.client_id }
      end,
    })
  end
})

I am satisfied, even when I receive the timeout warning. Congratulations on your great haskell-tools.nvim plugin my goal is for it to take care of everything related to haskell-language-server.