A .NET Dinosaur in Web3. Day 18 - Automated Market Maker

Olena Posted on May 31 • Originally published at Medium A .NET Dinosaur in Web3. Day 18 - Automated Market Maker # blockchain # smartcontract # ethereum # web3 A .NET Dinosaur in Web3 (16 Part Series) 1 A .NET Dinosaur in Web3. Day 1 - First Smart Contract 2 A .NET Dinosaur in Web3. Day 2 - Access Control ... 12 more parts... 3 A .NET Dinosaur in Web3. Day 3 - Voting, Sybil Attacks and Identity 4 A .NET Dinosaur in Web3. Day 4 - Writing My First Contract From Scratch 5 A .NET Dinosaur in Web3. Day 5 - First dApp. 6 A .NET Dinosaur in Web3. Day 6 - Wishlist or… “Dream Coins True”? 7 A .NET Dinosaur in Web3. Day 7 — First connect 8 A .NET Dinosaur in Web3. Day 8 — Reading & Writing — WishList Chain 9 A .NET Dinosaur in Web3. Day 9–10 — MVP of WishList Chain 10 A .NET Dinosaur in Web3. Day 11-12. Two projects, One Stack and What’s Next 11 A .NET Dinosaur in Web3. Day 13 — Access Control 12 A .NET Dinosaur in Web3. Day 14 — Pull Pattern vs Dangerous Push Payments 13 A .NET Dinosaur in Web3. Day 15 - DAO Voting 14 A .NET Dinosaur in Web3. Day 16 - ERC-20 Token & ICO 15 A .NET Dinosaur in Web3. Day 17 - Staking 16 A .NET Dinosaur in Web3. Day 18 - Automated Market Maker 🏦 Day 6 of 7: Building a Mini Uniswap in 80 Lines of Solidity Imagine a vending machine. It has 1,000 coffee beans and 1,000 coins. No menu, no cashier — just one iron rule: the product of the two numbers inside must never decrease. That's it! This is how Uniswap works — and this is what I built on Day 6, coming from .NET. Here's how, why it's elegant, and where you can step on a rake. Why an Order Book Doesn't Work on a Blockchain Traditional exchanges — Binance, NYSE, any CEX — run on an order book . Market makers post bids and asks. A matching engine pairs them. Millions of updates per second, all in a centralised database. In a blockchain, this is impossible. Transactions take 12 seconds. Every state change costs gas. Storing millions of constantly changing orders would eat all the profit