Editors

Raku in the tools you already use. The same rakupp binary that runs your programs checks them in your editor, runs them in a notebook and hands them to an AI agent.

Language server	How your editor talks to Raku++, and a live demo that shows every message as you type.
VS Code	The Raku++ extension from the Marketplace: mistakes underlined as you type, hover, completion, go to definition, syntax highlighting.
Emacs	The same, through eglot or lsp-mode, plus a Raku REPL in an Emacs buffer.
Neovim	The same language server, through Neovim's built-in LSP client.
WordPress	Code blocks in your posts that readers can edit and run.
Jupyter	Raku cells in JupyterLab, Notebook and VS Code notebooks.
Wolfram Language	Raku called from Mathematica and the Wolfram Engine, with values crossing as Wolfram expressions.
AI agents	Claude Code, Claude Desktop, Cursor and others run Raku and parse with grammars.

The language server #

VS Code, Emacs and Neovim all get their Raku support from one place: rakupp --lsp, a Language Server Protocol server built into rakupp. Its checks are the ones rakupp --lint runs, so the editor and the command line always agree. It reads your file but never runs it.

What it does

Mistakes underlined as you type: syntax errors, undeclared variables, unused variables, redundant return, unreachable code — each on the token it is about.
Hover: the declaration of the name under the cursor with its #| comment, or for a built-in, its entry in the reference.
Completion: variables in scope, your subs, classes and methods, keywords, and every built-in sub and method.
Go to definition: from a use of a name to where the file declares it.

How it works

The editor starts rakupp --lsp and the two talk in JSON messages over the server's standard input and output. The editor sends the file, then each change, and the server answers with the mistakes it found. Hover, completion and go to definition are questions: the editor sends the cursor position and the server sends back the answer.

Editor

rakupp --lsp

textDocument/didOpenhere is demo.raku

publishDiagnostics'@pionts' is not declared

textDocument/hoverwhat is at line 20, column 25?

responsemethod distance(): how far the point is from the origin

textDocument/completionwhat can follow $p.?

responsedistance, x, y, and the built-in methods

Six messages from the live demo.

Watch the language server at work The same server, running in your browser, with every message shown as you type. Nothing to install.

To use it in your editor, install rakupp and follow the section for your editor below. Version 5.2.1, the current release, gives the underlines. Hover, completion and go to definition arrive in the next release; until then they need a build of the repository.

VS Code #

Raku++ (rakupp) is on the Visual Studio Marketplace. Install it, and VS Code highlights your Raku files and checks them as you type.

Get Raku++ for VS Code

Or search for Raku++ in the Extensions view, or run:

code --install-extension DeepSoft.rakupp

The extension needs rakupp installed and starts it for you. If VS Code cannot find it — likely when you start VS Code from the Dock or Spotlight, which do not always see your shell's PATH — open your user settings as JSON (Command Palette → Preferences: Open User Settings (JSON)), add the path that command -v rakupp prints, and reload the window:

"rakupp.path": "/absolute/path/to/rakupp"

It highlights .raku, .rakumod, .rakutest, .p6 and .pm6 files.

Rather wire it up yourself? The extension is a thin client for rakupp --lsp, so any generic LSP client extension pointed at that command gets the same checks. To build the extension from source instead, see the full guide, which also has what you should see, and troubleshooting.

Emacs #

Emacs 29 or later, which has eglot and use-package built in. Add this to your init file (~/.emacs.d/init.el) and restart Emacs:

(require 'package)
(add-to-list 'package-archives '("melpa" . "https://melpa.org/packages/") t)

(use-package raku-mode
  :ensure t
  :custom (raku-exec-path "rakupp"))

(use-package eglot
  :hook (raku-mode . eglot-ensure)
  :config
  (add-to-list 'eglot-server-programs '(raku-mode . ("rakupp" "--lsp"))))

You get highlighting and indentation from raku-mode, everything the language server offers, and M-x run-raku: a REPL in a buffer that you can send lines, regions and whole files to. The Emacs guide also covers lsp-mode. Never used Emacs? Emacs 101 starts from installing it.

Neovim #

vim.lsp.start({
  name = "rakupp",
  cmd = { "rakupp", "--lsp" },
  filetypes = { "raku" },
  root_dir = vim.fn.getcwd(),
})

VS Code and Emacs are tested with the server; this Neovim setup is not yet. Any other editor with an LSP client works the same way: the command is always rakupp --lsp, over stdin and stdout.

WordPress #

The Raku Snippets plugin: install it, give a code block the class raku, and readers can edit the program and run it in the post. It runs in their browsers, so nothing runs on your server. For any other site, one script tag does the same.

Jupyter #

rakupp --jupyter-install
jupyter lab

Then pick Raku++ in the launcher. One interpreter serves the whole notebook, so a sub defined in one cell is callable in the next. You need Jupyter itself, and nothing more on the Raku side. The Jupyter guide has the details.

Wolfram Language #

Raku from Mathematica or the free Wolfram Engine, version 13.3 or newer. The binding is in Wolfram's own Paclet Repository as RakuppLink, packaged by Anton Antonov. In a notebook:

PacletInstall["AntonAntonov/RakuppLink"]
Needs["AntonAntonov`RakuppLink`"]

RakuppEval["[*] 1..20"]    (* 2432902008176640000, an exact Integer *)

Integers, strings and lists come back as their Wolfram counterparts, a hash as an Association, and a Raku grammar's match as a nested expression. The paclet finds the Raku++ library beside rakupp, so install rakupp first. The binding's guide has the rest, including using it straight from a checkout as RakuLang.wl.

AI agents #

rakupp --mcp serves the interpreter over the Model Context Protocol. In Claude Code:

claude mcp add raku -- "$(command -v rakupp)" --mcp

The agent gets two tools: raku, which evaluates code in one session that keeps its state between calls, and raku-parse, which compiles a grammar and returns the match as JSON, or the line, column and rule where it failed. The MCP guide covers Claude Desktop and other clients.