Neovim

Neovim has a built-in language server client, so no plugin is needed. It doesn’t know the .mc extension, though, so the setup registers the file type and then starts the server for it:

vim.filetype.add({ extension = { mc = "monkeyc" } })

vim.api.nvim_create_autocmd("FileType", {
  pattern = "monkeyc",
  callback = function(args)
    vim.lsp.start({
      name = "rafiki",
      cmd = { "rafiki", "server" },
      root_dir = vim.fs.root(args.buf, { "rafiki.toml", "manifest.xml", ".git" }) or vim.fn.getcwd(),
    })
  end,
})

Open a .mc file and diagnostics show up as you edit. Settings are best kept in the project’s rafiki.toml, but you can override the formatting ones by adding init_options = { lineWidth = 100 } to vim.lsp.start.

Format and fix on save

This applies every lint fix and then formats the file each time it’s saved:

vim.api.nvim_create_autocmd("BufWritePre", {
  pattern = "*.mc",
  callback = function()
    vim.lsp.buf.code_action({
      apply = true,
      async = false,
      context = { only = { "source.fixAll" } },
    })
    vim.lsp.buf.format()
  end,
})

Leave out the code_action call to only format. Fixes for a single finding are still available on demand through vim.lsp.buf.code_action().

If you use a plugin that manages formatting, like conform.nvim or none-ls, make sure it falls back to the language server for the monkeyc file type.

Troubleshooting

• Check that the server is attached with :checkhealth vim.lsp. If it isn’t, make sure :set filetype? prints monkeyc.
• If formatting on save does nothing, the file probably has a syntax error. :lua =vim.diagnostic.get(0) lists the diagnostics.
• Run :LspRestart after installing a new version of rafiki or changing rafiki.toml.
• For more detail, run :lua vim.lsp.set_log_level("debug") and read the log at vim.lsp.get_log_path().