how to set neovim for sml

vim.lsp.enable("millet")
version = 1
[workspace]
workspace.root = "foo.cm" # or sources.cm

Group is
  test.sml
  wawa.sml
  nana.sml
  {file-name.sml}
vim.api.nvim_create_autocmd("FileType", {
  pattern = "sml",
  callback = function()
    vim.bo.commentstring = "(* %s *)"
  end,
})