Merge pull request #34 from cs-pub-ro/defi

Add DeFi practical session

chapters/money/lab/content/mint_tokens.md

@@ -32,7 +32,7 @@ Let's create a token new token:
 
 ![Issue Token](../media/issue_token.png)
 
-and inspect the transaction 
+and inspect the transaction.
 
 ![Explorer Token Created](../media/explorer_token_created.png)
 

chapters/money/lab/content/swap.md

@@ -7,8 +7,57 @@ Keep in mind that Devnet and Testnet chains are different! First go to [Devnet W
 ![DEX](../media/xexchange.png)
 
 Use **Connect** button and connect with your wallet via your preferred method.
-After connection go to the **Swap** tab (it's located on the top of the page).
 
-![DEX](../media/swap.png)
+Let's perform a swap from EGLD to ASH.
 
-Select **USDC** and click **Swap**. Check the transaction on the Explorer. Check your balance on your Wallet.
+![SwapASH](../media/swap_ash1.png)
+Notice that for 1 EGLD, we would get **212 ASH** tokens.
+
+Let's try to swap more:
+![SwapASH](../media/swap_ash2.png)
+
+Notice that for 10 EGLD, we would get 1498 ASH tokens.
+That's **149.8 ASH** tokens for 1 EGLD.
+
+Any intuition of why the drop of exchange rate?
+
+Let's try to swap more:
+![SwapASH](../media/swap_ash3.png)
+
+Notice that for 100 EGLD, we would get 3798 ASH tokens.
+That's **37.98 ASH** tokens for 1 EGLD.
+
+## Automated Market Maker (AMM)
+
+An AMM relies on a mathematical formula to price assets.
+Instead of using an order book like a traditional exchange, assets are priced according to a pricing algorithm.
+
+This formula can vary with each protocol.
+For example, xExchange DEX uses the industry standard "x*y=k" constant product AMM model, which has proven its reliability in existing implementations, and has been formally modelled and verified.
+In this formula, k is a fixed constant, meaning the pool’s total liquidity always has to remain the same.
+
+![AMM](../media/amm.png)
+
+## Pair Smart Contract 
+
+The smart contract code can be found [here](https://github.com/multiversx/mx-exchange-sc/tree/main/dex/pair).
+
+Let's inspect the deployed [contract](https://devnet-explorer.multiversx.com/accounts/erd1qqqqqqqqqqqqqpgq0e9pmlzr0nk5nkulzcmessttsjkzr4xf0n4sue4r8e/tokens).
+
+![AshLPExplorer](../media/ash_lp_explorer.png)
+
+Notice the contract's balance:
+* WEGLD: 27.14
+* ASH: 4,817.99
+* ASHWEGLD: 0.000000000000001 - This is the token provided to liquidity providers when they add liquidity. Let's ignore this for now.
+
+Let's try to exchange more ASH than the contract can provide:
+
+![SwapASH](../media/swap_ash4.png)
+
+In this example, we tried to exchange **100 millions EGLD**, but the contract would output **4,580.0391 ASH** tokens.
+That's because of the curve of **x*y=k** formula (see image above).
+
+## Task
+Perform a swap. Go to the [Explorer](https://devnet-explorer.multiversx.com) and inspect your transaction.
+Inspect if there are any evets emitted.

chapters/smart-contracts/lab/content/events.md

@@ -1,5 +1,7 @@
 # Events
 
+In this section you will learn what Smart Contract Events are, how to see what events were emitted in a transaction and how to emit one yourself.
+
 Key Takeaways:
 * Events in smart contracts serve as a communication mechanism between the contract and user interfaces;
 * By emitting events, smart contracts can notify external applications or listeners about specific actions or changes;

config.yaml

@@ -122,20 +122,26 @@ docusaurus:
                 - ../media/
               subsections:
                 - Building your first dApp: dApp.md
+          - Smart Contract Events:
+              path: chapters/smart-contracts/lab/content/
+              subsections:
+                - SC Events: events.md
+              extra:
+                - ../media/
+          - DeFi:
+              path: chapters/money/lab/content/
+              extra:
+                - ../media/
+              subsections:
+                - ESDT Tokens: mint_tokens.md
+                - Swap Tokens: swap.md
           - Observer:
               path: chapters/introduction/lab/content/observer/
               extra:
                 - ../../media/
                 # - ../../quiz/
               subsections:
                 - Observers: observer.md
-          - Money (DeFi):
-              path: chapters/money/lab/content
-              extra:
-                - ../media/
-              subsections:
-                - ESDT Tokens: mint_tokens.md
-                - Swap Tokens: swap.md
           - Basic Peer-to-Peer Blockchain:
               path: chapters/peer-to-peer/lab/content
               subsections:
@@ -150,33 +156,6 @@ docusaurus:
                 - Sources : sources.md
               extra:
                 - ../media/
-          - Smart Contract Events:
-              path: chapters/smart-contracts/lab/content
-              subsections:
-                - SC Events: events.md
-              extra:
-                - ../media/
-
-      #     - Fungible Tokens:
-      #         path: chapters/template-chapter/yet-another-topic/
-      #         subsections:
-      #           - Drills/: drills/
-      #     - Non Fungible Tokens (NFT):
-      #         path: chapters/template-chapter/yet-another-topic/
-      #         subsections:
-      #           - Drills/: drills/
-      #     - dApps:
-      #         path: chapters/template-chapter/yet-another-topic/
-      #         subsections:
-      #           - Drills/: drills/
-      #     - Security:
-      #         path: chapters/template-chapter/yet-another-topic/
-      #         subsections:
-      #           - Drills/: drills/
-      #     - DeFi:
-      #         path: chapters/template-chapter/yet-another-topic/
-      #         subsections:
-      #           - Drills/: drills/
       - Assignments:
           - Assignment 1: assignments/assignment1.md
           - Assignment 2: assignments/assignment2.md