The Leo Programming Language

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

Table of Contents

• 1. Overview
• 2. Build Guide
  • 2.1 Install Rust
  • 2.2a Build from Crates.io
  • 2.2b Build from Source Code
• 3. Quick Start
• 4. Documentation
• 5. Contributing
• 6. License

1. 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. If your goal is to build a user experience on the web that is both truly personal and truly private, then we recommend downloading the Aleo Studio IDE and checking out the Aleo Package Manager.

2. Build Guide

2.1 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.

2.2a Build from Crates.io

We recommend installing Leo this way. In your terminal, run:

cargo install leo-lang

Now to use Leo, in your terminal, run:

leo

2.2b Build from Source Code

Alternatively, you can install Leo by building from the source code as follows:

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

# Build in release mode
$ cargo build --release

This will generate an executable under the ./target/release directory. To run Leo, run the following command:

./target/release/leo

3. Quick Start

Use the Leo CLI to create a new project

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

# build & setup & prove & verify
leo run

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

The leo run command will compile the main program, generate keys for a trusted setup, fetch inputs, generate a proof and verify it.

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

4. Documentation

• Hello World - Next Steps
• Leo Language Documentation
• Leo ABNF Grammar
• Leo CLI Documentation
• Homepage

5. Contributing

Please see our guidelines in the developer documentation

Thank you for helping make Leo better!

6. License