Solidity is a contract-oriented, high-level programming language for creating smart contracts. It was influenced by C++, Python, and JavaScript and is designed to target the Ethereum Virtual Machine (EVM) environments. Solidity is statically typed, supports inheritance, and libraries. It allows developers to create smart contracts for a wide range of use cases and applications. Key features of Solidity include:
  • Complex user-defined types
  • Inheritance and complex user-defined contracts
  • Error checking, including requirements and assertions
  • Support for libraries and user-defined functions
  • Strong security features that ensure the contract integrity

Example Contract

The Greeter contract shown below is written with Solidity v0.8.0. Greeter serves two functions:
  • Store a greeting on-chain
  • Return the greeting when the contract function is called
It also contains a function for users to set a new greeting of their choice. While the Greeter contract may be simple, it showcases some of the unique functionality that smart contracts offer.
pragma solidity ^0.8.0;
contract Greeter {
string private greeting;
function greet() public view returns (string memory) {
return greeting;
function setGreeting(string memory _greeting) public {
console.log("Changing greeting from '%s' to '%s'", greeting, _greeting);
greeting = _greeting;


Alternative Languages

The EVM supports a wide variety of other languages such as Yul and Yul+, Huff, and Vyper through the use of compilers/transpilers. Yul and Huff are lower level languages that offer developers the ability to write assembly-like syntax or direct bytecode. Vyper is a higher level language more akin to Solidity that makes the move from Python to smart contract development significantly easier for developers.
For any of the above languages to be used on Quai Network, support for Quai's additional EVM opcodes isaddrInternal and etx must be added to their respective compilers. More details on using the Quai specific opcodes can be found on the Opcode Additions page. Quai Network intends to provide full opcode support for these alternative languages in the future.