Leo for Visual Studio Code

The Leo Programming Language

Leo is a functional, statically-typed programming language built for writing private applications.

🍎 Overview
⚙️️ Build Guide
🚀 Quick Start
🧰 Troubleshooting
📖 Documentation
🤝 Contributing
❤️ Contributors
🛡️ License

🍎 Overview

Welcome to the Leo programming language.

Leo provides a high-level language that abstracts low-level cryptographic concepts and makes it easy to integrate private applications into your stack. Leo compiles to circuits making zero-knowledge proofs practical.

The syntax of Leo is influenced by traditional programming languages like JavaScript, Scala, and Rust, with a strong emphasis on readability and ease-of-use. Leo offers developers with tools to sanity check circuits including unit tests, integration tests, and console functions.

Leo is one part of a greater ecosystem for building private applications on Aleo. The language is currently in an alpha stage and is subject to breaking changes.

🧩 Current VS Code Support

This extension is the new minimal Leo client and will continue publishing to the existing aleohq.leo-extension marketplace entry.

Today it supports:

.leo file association
syntax highlighting generated from Leo's tree-sitter source in the main ProvableHQ/leo repo
comment, bracket, and editor language configuration for Leo files
optional leo-lsp startup for semantic tokens and go-to-definition when the binary is installed locally
approximate client-side go-to-definition fallback when leo-lsp is unavailable

🛠️ Migration Status

The previous LSP-backed implementation is being replaced as part of the migration to faster Rust-based Leo tooling.

Validation, completion, and related language features are not gone permanently. They are expected to return incrementally in future extension updates as the new Leo tooling stack lands.

🖱️ Installing in Cursor

Cursor is a downstream fork of VS Code that pulls extensions from Open VSX. The same aleohq.leo-extension VSIX ships to both registries.

Open Cursor's Extensions pane (Cmd+Shift+X), search for Leo, and click Install. The extension activates on .leo files, registers syntax highlighting, and starts leo-lsp over stdio if a binary is discoverable on PATH — falling back to the client-side regex go-to-definition provider when it is not.

🪐 Installing in Antigravity

Google Antigravity (antigravity.google) ships as two macOS app bundles:

/Applications/Antigravity.app: the Hub launcher (Google's agent shell). The installer drops this first.
/Applications/Antigravity IDE.app: the VS Code-style IDE fork that loads extensions. The Hub's first-run wizard installs this separately.

If you only see Antigravity.app, the IDE half hasn't been installed yet. Re-open the Hub and complete its IDE install wizard.

Once both are installed, open Antigravity IDE (not the Hub), then its Extensions pane, search for Leo, and click Install. The IDE consumes the same aleohq.leo-extension Open VSX listing as Cursor, so there is no separate Antigravity package or marketplace listing.

The extension activates on .leo files, registers syntax highlighting, and starts leo-lsp over stdio if a binary is discoverable on PATH, falling back to the client-side regex go-to-definition provider when it is not.

🚀 Quick Start

Use the Leo CLI to create a new project

# create a new `hello-world` Leo project
leo new helloworld
cd helloworld

# build & setup & prove & verify
leo run main 0u32 1u32

The leo new command creates a new Leo project with a given name.

The leo run command will compile the program into Aleo instructions and run it.

Congratulations! You've just run your first Leo program.

⚙️️ Build Guide

🦀 Install Rust

We recommend installing Rust using rustup. You can install rustup as follows:

macOS or Linux:

curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh

Windows (64-bit):

Download the Windows 64-bit executable and follow the on-screen instructions.
Windows (32-bit):

Download the Windows 32-bit executable and follow the on-screen instructions.

🐙 Build from Source Code

We recommend installing Leo by building from the source code as follows:

# Download the source code
git clone https://github.com/ProvableHQ/leo
cd leo

# Install 'leo'
$ cargo install --path .

Now to use leo, in your terminal, run:

leo

🦁 Update from Leo

You can update Leo to the latest version using the following command:

leo update

Now to check the version of leo, in your terminal, run:

leo --version

🧰 Troubleshooting

If you are having trouble installing and using Leo, please check out our guide.

If the issue still persists, please open an issue.

📖 Documentation

🤝 Contributing

Please see our guidelines in the developer documentation

❤️ Contributors

View all Leo contributors here.

Leo

aleohq