DeFi, short for Decentralized Finance, is a prominent use case for blockchain technology. Among the many protocols that exist, Uniswap was one of the earliest to implement the automatic market maker (AMM) model and remains one of the most widely used solutions to date.<\/p>\n\n
To develop our solution, we have chosen to use Vyper. This is because it offers clear readability, built-in security features, and optimization capabilities right out of the box. By leveraging Vyper, we aim to enhance the overall quality and reliability of our code.<\/p>\n\n
Automated market makers (AMMs) are part of the decentralized finance (Defi) ecosystem. They allow digital assets to be traded in a permissionless and automatic way by using liquidity pools rather than a traditional market of buyers and sellers. AMM users supply liquidity pools with crypto tokens, whose prices are determined by a constant mathematical formula. Liquidity pools can be optimized for different purposes, and are proving to be an important instrument in the Defi ecosystem. In this tutorial, we are going to use a constant-product AMM.<\/a><\/p>\n\n For this particular project, we have decided to use ApeWorx, a novel framework for smart contract development that utilizes Python. We chose ApeWorx for its simplicity, ease of use, and powerful capabilities. Additionally, the framework supports plugins, allowing us to extend its functionality and enhance our development process even further.<\/p>\n\n By leveraging ApeWorx, we aim to streamline our smart contract development workflow, improve the readability of our code, and maximize the efficiency of our development efforts. We believe that ApeWorx's advanced features and flexibility will allow us to build high-quality smart contracts that meet our specific needs and requirements.<\/p>\n\n To begin using ApeWorx for this project, you will need to have Python installed along with a virtual environment. You can set up these prerequisites by following the links provided.<\/p>\n\n If you are new to this process, do not be intimidated. The setup process is simple, and we are confident that you will be able to get started quickly. With the necessary tools in place, we can begin leveraging ApeWorx's powerful features to build robust and reliable smart contracts.<\/p>\n\n To start creating our project, we first need to create a new folder called uviswap<\/strong> and navigate to it using the terminal: Now we need to create a Python Virtual Enviroment<\/a>, this is to keep our dependencies isolated from other packages. And we install our packages, in this case, we just need to install ApeWorx<\/a>. Next, we will initialize a new ApeWorx project and name it uviswap<\/strong>: \ud83d\udea7 If you encounter the issue of Finally, we need to install Vyper as a plugin so that we can work with it using ApeWorx. Fortunately, the process is straightforward to understand, and can be accomplished using a single command: Great! With our project now set up, we can move on to implementing the smart contracts.<\/p>\n\n For this DeFi application, we will define two smart contracts: the Pair and the Factory.<\/p>\n\n The Pair<\/strong> contract is the heart of our automated market maker project and will be responsible for holding a pair of tokens.<\/p><\/li>\n The Factory<\/strong> contract will be responsible for creating new pairs using new tokens or returning the address of a pair if it already exists.<\/p><\/li>\n<\/ul>\n\n Together, these contracts will form the backbone of our DeFi application and allow us to implement our automated market-maker model.<\/p>\n\n To begin implementing the Pair contract, we will create a new file named UviswapPair.vy<\/strong> in the contracts\/<\/strong> directory. We will specify the Vyper version as ^0.3.10<\/strong> and import the ERC20 and ERC20 Detailed interfaces from Vyper.<\/p>\n\n This boilerplate code will provide us with the basic foundation for developing our Pair contract. This is our basic boilerplate, we need the ERC20 definition to allow our users to use their shares however they want.\n \n \n Setup project\n<\/h2>\n\n
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\n<\/p>\n\n$ <\/span>mkdir <\/span>uviswap\n$ <\/span>cd<\/span> .\/uviswap\n<\/code><\/pre>\n\n<\/div>\n\n\n\n
\n<\/p>\n\n$ <\/span>python3 -m<\/span> venv .venv\n$ <\/span>source<\/span> .venv\/bin\/activate\n$ <\/span>pip install <\/span>eth-ape\n<\/code><\/pre>\n\n<\/div>\n\n\n\n
\n<\/p>\n\n$ <\/span>ape init\n$ <\/span>Please enter project name: uviswap\n<\/code><\/pre>\n\n<\/div>\n\n\n\n\n
No module named 'pkg_resources'<\/code>, you need to run pip install setuptools<\/code> to fix it.<\/p>\n<\/blockquote>\n\n
\n<\/p>\n\n$ <\/span>ape plugins install <\/span>vyper\n<\/code><\/pre>\n\n<\/div>\n\n\n\n\n \n \n Smart contract development\n<\/h2>\n\n
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\n \n \n UviswapPair\n<\/h3>\n\n
\n<\/p>\n\n# pragma version ^0.3.10\n<\/span>\nfrom<\/span> vyper.interfaces<\/span> import<\/span> ERC20<\/span>\nfrom<\/span> vyper.interfaces<\/span> import<\/span> ERC20Detailed<\/span>\n\nimplements<\/span>:<\/span> ERC20<\/span>\nimplements<\/span>:<\/span> ERC20Detailed<\/span>\n<\/code><\/pre>\n\n<\/div>\n\n\n\n
\n<\/p>\n\n# pragma version ^0.3.10\n<\/span>\nfrom<\/span> vyper.interfaces<\/span> import<\/span> ERC20<\/span>\nfrom<\/span> vyper.interfaces<\/span> import<\/span> ERC20Detailed<\/span>\n\n###### EVENTS ######\n<\/span>\nevent<\/span> Transfer<\/span>:<\/span>\n sender<\/span>:<\/span> indexed<\/span>(<\/span>address<\/span>)<\/span>\n receiver<\/span>:<\/span> indexed<\/span>(<\/span>address<\/span>)<\/span>\n value<\/span>:<\/span> uint256<\/span>\n\nevent<\/span> Approval<\/span>:<\/span>\n owner<\/span>:<\/span> indexed<\/span>(<\/span>address<\/span>)<\/span>\n spender<\/span>:<\/span> indexed<\/span>(<\/span>address<\/span>)<\/span>\n value<\/span>:<\/span> uint256<\/span>\n\n###### STATE ######\n<\/span>\n# Share token name\n<\/span>name<\/span>:<\/span> public<\/span>(<\/span>String<\/span>[<\/span>32<\/span>])<\/span>\n\n# Share token symbol\n<\/span>symbol<\/span>:<\/span> public<\/span>(<\/span>String<\/span>[<\/span>32<\/span>])<\/span>\n\n# Share token decimals\n<\/span>decimals<\/span>:<\/span> public<\/span>(<\/span>uint8<\/span>)<\/span>\n\n# By declaring `balanceOf` as public, vyper automatically generates a 'balanceOf()' getter\n# method to allow access to account balances.\n<\/span>balanceOf<\/span>:<\/span> public<\/span>(<\/span>HashMap<\/span>[<\/span>address<\/span>,<\/span> uint256<\/span>])<\/span>\n\n# By declaring `allowance` as public, vyper automatically generates the `allowance()` getter\n<\/span>allowance<\/span>:<\/span> public<\/span>(<\/span>HashMap<\/span>[<\/span>address<\/span>,<\/span> HashMap<\/span>[<\/span>address<\/span>,<\/span> uint256<\/span>]])<\/span>\n\n# By declaring `totalSupply` as public, we automatically create the `totalSupply()` getter\n<\/span>totalSupply<\/span>:<\/span> public<\/span>(<\/span>uint256<\/span>)<\/span>\n\n###### CONSTRUCTOR ######\n<\/span>@external<\/span>\ndef<\/span> __init__<\/span>():<\/span>\n self<\/span>.<\/span>name<\/span> =<\/span> \"<\/span>Uviswap<\/span>\"<\/span>\n self<\/span>.<\/span>symbol<\/span> =<\/span> \"<\/span>UVI<\/span>\"<\/span>\n self<\/span>.<\/span>decimals<\/span> =<\/span> 18<\/span>\n\n\n###### INTERNAL METHODS ######\n<\/span>@internal<\/span>\ndef<\/span> _mint<\/span>(<\/span>_to<\/span>:<\/span> address<\/span>,<\/span> _value<\/span>:<\/span> uint256<\/span>):<\/span>\n assert<\/span> _to<\/span> !=<\/span> empty<\/span>(<\/span>address<\/span>),<\/span> \"<\/span>ERC20: mint to the zero address<\/span>\"<\/span>\n self<\/span>.<\/span>balanceOf<\/span>[<\/span>_to<\/span>]<\/span> +=<\/span> _value<\/span>\n self<\/span>.<\/span>totalSupply<\/span> +=<\/span> _value<\/span>\n log<\/span> Transfer<\/span>(<\/span>empty<\/span>(<\/span>address<\/span>),<\/span> _to<\/span>,<\/span> _value<\/span>)<\/span>\n\n\n@internal<\/span>\ndef<\/span> _burn<\/span>