## Introduction to Solidity and Vyper We'll start with an introduction to the smart contract programming languages Solidity and Vyper. We'll learn about the differences between these languages and what they're commonly used for. First, let's see how many people are familiar with Solidity and Vyper. It's worth knowing that Solidity is probably the most popular smart contract programming language. This is because Solidity is used to develop smart contracts for the Ethereum Blockchain. Vyper is another language that's also used for Ethereum smart contracts, but it's less popular. This is because Vyper is a more secure language and can be considered a more secure alternative to Solidity. We'll discuss why Vyper is more secure than Solidity as we go through the course. Now, let's get started with our first example. In Solidity, the first thing we'll always see is the pragma statement. In the following example, we're targeting Solidity version 0.8.26 and this is a common statement that we'll see in many smart contracts. ```javascript pragma solidity ^0.8.26; ``` This statement is important because it ensures that the smart contract code is compatible with the specified version of the Solidity compiler. If you are using an incompatible version, your smart contract code will not compile. We'll also see that there are various Solidity versions. These versions differ in terms of features and the available syntax, so it's crucial to use the correct version for your project. The next thing we'll see is the contract definition. In this case, we're defining a contract named "MyContract." Solidity supports the use of inheritance. ```javascript contract MyContract { } ``` This example defines a simple contract named "MyContract" which we can deploy onto a blockchain to store and update state variables and execute functionality. Now let's look at a simple Vyper example. ```javascript # pragma solidity ^0.8.26 from vyper.interfaces import ERC20 interface IUniswapV2Pair: def getReserves() -> tuple: pass interface IUniswapV2Factory: def getPair(tokenA: address, tokenB: address) -> address: pass def get_pair(factory: address, tokenA: address, tokenB: address) -> address: """ Get the UniswapV2 pair address for two tokens. """ return IUniswapV2Factory(factory).getPair(tokenA, tokenB) ``` This code contains several interesting elements: 1. The first line indicates that the Vyper compiler version is `0.8.26`. 2. It imports the `ERC20` interface from `vyper.interfaces`. 3. It defines a custom interface `IUniswapV2Pair` to allow interacting with UniswapV2 pair contracts. 4. It defines another interface `IUniswapV2Factory` to interact with UniswapV2 factory contracts. 5. Finally, it defines a function `get_pair` to return the UniswapV2 pair address for two given tokens. We can also see that Vyper is a very different language compared to Solidity. Let's go through a quick comparison of Solidity and Vyper: * **Solidity** is a Turing-complete language which means it's powerful but can be complex and susceptible to errors. * **Vyper** is a more limited language that can be easier to use and more secure. The next topic we'll cover is the concept of smart contracts.