fuellabs/sway

Sway is a programming language purpose-built for writing smart contracts on the Fuel blockchain. A smart contract is a program that runs on a blockchain and automatically executes when certain conditions are met, like a vending machine that accepts a coin and releases a product without needing a person to operate it. The problem Sway addresses is that existing smart contract languages have safety and developer-experience limitations, and Fuel needed a language that could take full advantage of its own high-performance blockchain architecture. Sway is heavily inspired by Rust, borrowing its syntax, type system, and approach to safety. Like Rust, it aims to catch errors at compile time before the code is ever deployed, reducing the risk of costly bugs in live contracts. It comes with its own toolchain called Forc (Fuel Orchestrator), which handles compiling, testing, and deploying Sway programs. The language includes a standard library, and the project also provides extensive documentation through the Sway Book. You would use Sway if you are building decentralized applications on the Fuel network, for example, writing a token contract, a decentralized exchange, or any other on-chain logic. It is not a general-purpose language and is specifically designed for the Fuel blockchain environment. The tech stack is Rust used to build the Sway compiler itself; Sway code you write compiles to Fuel VM bytecode for deployment on the Fuel blockchain. Installation is through Rust's Cargo package manager.