nvim-lspconfig/lua/lspconfig/configs/haxe_language_server.lua

-- !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
-- This config is DEPRECATED.
-- Use the configs in `lsp/` instead (requires Nvim 0.11).
--
-- ALL configs in `lua/lspconfig/configs/` will be DELETED.
-- They exist only to support Nvim 0.10 or older.
-- !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
local util = require 'lspconfig.util'

local function find_hxml(path)
  return vim.fs.find(function(name)
    return name:match '.hxml$'
  end, { path = path, type = 'file' })
end

return {
  default_config = {
    cmd = { 'haxe-language-server' },
    filetypes = { 'haxe' },
    root_dir = util.root_pattern('*.hxml', '.git'),
    settings = {
      haxe = {
        executable = 'haxe',
      },
    },
    -- Default value is set by on_new_config.
    init_options = {},
    on_new_config = function(new_config, new_root_dir)
      if new_config.init_options.displayArguments then
        return
      end

      local hxml = find_hxml(new_root_dir)[1]
      if hxml then
        vim.notify('Using HXML: ' .. hxml)
        new_config.init_options.displayArguments = { hxml }
      end
    end,
  },
  docs = {
    description = [[
https://github.com/vshaxe/haxe-language-server

The Haxe language server can be built by running the following commands from
the project's root directory:

    npm install
    npx lix run vshaxe-build -t language-server

This will create `bin/server.js`. Note that the server requires Haxe 3.4.0 or
higher.

After building the language server, set the `cmd` setting in your setup
function:

```lua
lspconfig.haxe_language_server.setup({
  cmd = {"node", "path/to/bin/server.js"},
})
```

By default, the language server is configured with the HXML compiler arguments
contained in the first `.hxml` file found in your project's root directory.
If you want to specify which one to use, set the `init_options.displayArguments`
setting:

```lua
lspconfig.haxe_language_server.setup({
  -- ...
  init_options = {
    displayArguments = { "build.hxml" },
  },
})
```

]],
  },
}