ZZLS - Zig Language Server

A fast Zig language server written in Rust, targeting Zig 0.16.x.

Disclaimer;

This is AI slop. Do not be fooled by the readme that this is actually functioning, it is slop and should not be taken seriously nor used by anyone in any real context.

Features

• Diagnostics via zig ast-check (fast syntax) and zig build-exe -fno-emit-bin (full semantic)
• Format on save via zig fmt --stdin
• Format on demand via textDocument/formatting and textDocument/rangeFormatting
• Completion (basic keyword completions, more to come)
• Document symbols (fn, struct, enum, const, var declarations)
• Go to definition/declaration
• Find references
• Rename
• Code actions
• Pretty terminal diagnostics via ariadne (CLI mode)

Installation

cargo install --path .

Make sure zig is in your PATH, or configure the path in your editor settings.

Usage

LSP Server (default)

zzls --stdio

CLI Check

zzls check path/to/file.zig

CLI Format

# Format a file in-place
zzls format path/to/file.zig

# Check if formatting is needed (exit code 1 if changes needed)
zzls format --check path/to/file.zig

Neovim Setup

ZZLS works with Neovim's native LSP client (vim.lsp). Add the config file lsp/zzls.lua to your Neovim config directory:

-- ~/.config/nvim/lsp/zzls.lua
---@type vim.lsp.Config
return {
  cmd = { 'zzls', '--stdio' },
  filetypes = { 'zig', 'zon' },
  root_markers = { 'build.zig', 'build.zig.zon', '.git' },
  settings = {
    zzls = {
      zig_path = nil, -- auto-detect from PATH
      format_on_save = true,
      diagnostics_on_save = true,
      diagnostics_debounce_ms = 200,
    },
  },
}

Then in your LSP setup:

vim.lsp.enable({ 'zzls' })

Keymaps

ZZLS integrates with your existing LSP keymaps:

Key	Mode	Action
K	n	Hover documentation
<C-k>	i	Signature help
gd	n	Go to definition
gD	n	Go to declaration
<leader>rn	n	Rename symbol
<leader>la	n	Code actions
<leader>lf	n	Format document
gr	n	Find references
<leader>ls	n	Document symbols

Configuration

Settings can be configured via vim.lsp.config('zzls', { settings = { ... } }):

Setting	Type	Default	Description
zig_path	string?	nil	Path to zig binary (auto-detect from PATH if nil)
format_on_save	bool	true	Format file on save
diagnostics_on_save	bool	true	Run diagnostics on save
diagnostics_on_change	bool	false	Run diagnostics on every change
diagnostics_debounce_ms	number	200	Debounce delay for diagnostics

Architecture

src/
├── main.rs           # CLI entry point (server/check/format subcommands)
├── server.rs         # LSP server implementation (LanguageServer trait)
├── document.rs       # Document/buffer management with ropey
├── workspace.rs      # Workspace/project detection
├── config.rs         # Configuration handling
├── bridge/
│   ├── mod.rs
│   ├── compiler.rs   # Zig compiler integration (ast-check + build-exe)
│   └── formatter.rs  # zig fmt integration
└── diagnostics/
    ├── mod.rs        # Diagnostic types and LSP conversion
    └── pretty.rs     # Ariadne-based pretty printing

Dependencies

• tower-lsp-server - LSP framework
• ls-types - LSP type definitions
• ropey - Rope data structure for text editing
• tokio - Async runtime
• ariadne - Pretty error reporting
• clap - CLI argument parsing

License

MIT