Language Server & Tooling

Nulang ships a built-in language server implementing the Language Server Protocol (LSP) over stdio, plus a TextMate grammar, a formatter, and a debug adapter. Point any LSP-capable editor at nulang --lsp for .nula files.

Language Server

Start the server with:

nulang --lsp

It speaks LSP over stdin/stdout (Content-Length framed JSON-RPC). The server is included in default builds (the lsp cargo feature, on by default).

Features

Feature	Description
Diagnostics	Parse/type/effect/capability errors, pushed on open and save
Hover	Function signatures, effects, types, doc comments
Go to Definition	All declaration types
References	Find all usages of a symbol
Document Symbols	Structured outline (functions, actors, behaviors, …)
Rename	With prepareRename
Signature Help	Parameter hints while typing
Formatting	Indentation-based code formatting
Semantic Tokens	Editor-side syntax highlighting
Code Actions	Quick fixes (add type annotations)
Inlay Hints	Inferred types, capabilities, effect rows, return types
Completion	Keywords, effects, capabilities, functions (triggers . and ::)
Code Lens	Reference counts on top-level declarations
Document Links	Clickable import paths to stdlib/files

Requirements

The nulang binary must be reachable from your editor’s LSP client. The server keeps stdout pure JSON-RPC — all logging goes to stderr — so any client that spawns nulang --lsp works without special handling.

VS Code

The Nulang extension provides syntax highlighting plus the full language server surface (diagnostics, hover, go-to-definition, references, rename, completion, signature help, inlay hints, formatting, and more).

See Editor Setup for installation and configuration, including the nulang.path setting.

Other Editors

Any editor with LSP client support can talk to nulang --lsp over stdio:

• Neovim — nvim-lspconfig:

  vim.api.nvim_create_autocmd('FileType', {
    pattern = 'nula',
    callback = function()
      vim.lsp.start({ name = 'nulang', cmd = { 'nulang', '--lsp' } })
    end,
  })

• Emacs — lsp-mode or eglot:

  (add-to-list 'eglot-server-programs '(nula-mode . ("nulang" "--lsp")))

• Helix — add to languages.toml:

  [[language]]
  name = "nulang"
  scope = "source.nulang"
  file-types = ["nula"]
  language-server = { command = "nulang", args = ["--lsp"] }

• Zed — add to settings.json:

  {
    "languages": {
      "Nulang": {
        "language_servers": ["nulang-lsp"]
      }
    },
    "lsp": {
      "nulang-lsp": { "binary": { "path": "nulang", "arguments": ["--lsp"] } }
    }
  }

Syntax Highlighting

The TextMate grammar (source.nulang) lives in its own repository, nulang-org/nulang-syntax, and is consumed by the VS Code extension. Any TextMate-compatible editor (Sublime Text, TextMate, …) can load syntaxes/nulang.tmLanguage.json directly.

Formatter

nulang fmt [--check] [<file>]

Formats a file in place (or checks formatting with --check). The language server exposes the same formatter via textDocument/formatting.

Debug Adapter

nulang --dap

Speaks the Debug Adapter Protocol over stdio (the same Content-Length framing as the LSP), so editors such as VS Code can debug .nula programs: source breakpoints, continue/step-in/step-over/step-out, pause, stack traces, scope and local-variable inspection, and evaluate.