LSP

What is LSP?

The Language Server Protocol (LSP) is a standardized protocol that allows editors and IDEs to communicate with language-specific servers. These servers provide features like:

• Code completion
• Syntax highlighting
• Error detection (diagnostics)
• Go-to-definition
• Refactoring tools
• Documentation on hover

LunarVim leverages LSP via nvim-lspconfig and mason.nvim, simplifying server installation and configuration.

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Step 1: Installing Language Servers

LunarVim uses Mason to manage LSP servers, linters, formatters, and other tools. Here’s how to install a language server:

1. Open Mason: Run :Mason to open the plugin’s interface.
2. Install a Server: Navigate to the server you need (e.g., pyright for Python, tsserver for TypeScript) and press i.
3. Verify Installation: Run :LspInfo to confirm the server is installed and active.

Alternatively, install servers via the command line:

:LspInstall pyright

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Step 2: Configuring LSP in LunarVim

LunarVim pre-configures LSP for many languages, but you can customize settings in your config.lua (~/.config/lvim/config.lua).

Example: Customizing Python (pyright)

vim.list_extend(lvim.lsp.automatic_configuration.skipped_servers, { "pyright" }) -- Disable default setup
 
lvim.lsp.automatic_configuration.skipped_servers = { "tsserver" } -- Skip default setup for TS
 
require("lvim.lsp.manager").setup("pyright", {
  on_attach = function(client, bufnr)
    -- Custom keybindings or logic here
  end,
  settings = {
    python = {
      analysis = {
        typeCheckingMode = "strict", -- Enforce strict type checks
      },
    },
  },
})

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Step 3: Keybindings and Usage

LunarVim sets up default keybindings for LSP features. Here are the essentials:

• K: Show documentation hover.
• gd: Go to definition.
• gr: List references.
• <leader>ca: Code actions (e.g., fix suggestions).
• [d/]d: Jump between diagnostics.

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Step 4: Refactoring with LSP

LSP enables powerful refactoring capabilities directly in LunarVim. Here’s how to leverage them:

Rename Symbols

• Keybinding: Use <leader>rn (if configured) to rename a symbol across your project.

  lvim.lsp.buffer_mappings.normal_mode['<leader>rn'] = { vim.lsp.buf.rename, 'Rename Symbol' }

• Usage: Place cursor on the symbol, press <leader>rn, and enter the new name.

Code Actions

• Default Keybinding: <leader>ca opens a list of available code actions, including refactorings.
• Common Refactorings:
  • Extract Variable/Function: Select the code, trigger <leader>ca, and choose the extraction.
  • Organize Imports: Automatically sort and clean up imports (available in many language servers).

Example: TypeScript with tsserver

1. Extract to Function:

   • Highlight a code block.
   • Press <leader>la and select “Extract to function”.

2. Organize Imports:

   • Press <leader>la in a TypeScript file and choose “Organize Imports”.

Notes:

• Server Support: Refactoring options depend on your language server. Check server documentation for available features.
• Troubleshooting: If refactorings don’t appear, ensure your language server supports them via :LspInfo.

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Step 5: Diagnostics and Formatting

Diagnostics

• View errors with :lua vim.diagnostic.open_float().
• Toggle diagnostics globally with :lua vim.diagnostic.disable()/:enable().

Formatting

LunarVim uses LSP or null-ls for formatting. Enable formatting on save:

lvim.format_on_save = true

To specify a formatter:

local formatters = require("lvim.lsp.null-ls.formatters")
formatters.setup({
  { command = "black", filetypes = { "python" } }, -- Python formatter
  { command = "prettier", filetypes = { "javascript", "typescript" } },
})

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Step 6: Advanced Setup with null-ls

Some tools (linters, formatters) aren’t LSP servers. Use null-ls to integrate them:

1. Install via Mason (:MasonInstall eslint_d prettier).
2. Configure in config.lua:

local null_ls = require("null-ls")
null_ls.setup({
  sources = {
    null_ls.builtins.diagnostics.eslint_d, -- JS/TS linter
    null_ls.builtins.formatting.stylua, -- Lua formatter
  },
})

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Step 7: Troubleshooting Common Issues

1. Server Not Starting:

   • Run :LspInfo to check if the server is active.
   • Verify installation with :Mason.

2. Diagnostics Missing:

   • Ensure the server supports diagnostics (e.g., pyright does, tsserver requires eslint).

3. Conflicting Servers:

   • Skip default setup for languages with multiple servers:

     vim.list_extend(lvim.lsp.automatic_configuration.skipped_servers, { "jedi_language_server" })

4. Logs and Debugging:

   • Check Neovim’s LSP logs: :LspLog.

5. Restarting LSP Servers:

   • If your LSP server stops responding or fails to update after file changes, manually restart it with:

   :LspRestart