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
  • 2.2 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. The language is currently in an alpha stage and is subject to breaking changes.

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.

2.2 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/AleoHQ/leo
cd leo

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

Now to use leo, in your terminal, run:

leo

3. 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

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.

4. Documentation

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

5. Contributing

Please see our guidelines in the developer documentation

Thank you for helping make Leo better!

6. License