challenge_3.md

Challenge 3 - Starting our bot and modelling Uniswap V2

Last week we've managed to index the data we need to simulate Jediswap - Uniswap V2 implementation. This week, we will start coding our bot and implement our off-chain model to simulate swap.

Note

The bot can be written in any language you want, but ideally a language with a good MongoDB library and a good Starknet library.

Here is a proposition of the bot architecture but you are free to implement it entierely differently. Nonetheless, the exercises below are written based on the assumption that you are following the diagram.

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Exercise 1

Implement the $Pool$ type that store the data we've indexed and exposes at least the following methods

- swap(from, amount_in) -> float // implement the swap function of Uniswap V2
- apply_swap(amount_in) -> float // do the same as swap but modify the reserves
- estimate_price(from) -> float // estimate swap(from, 1)

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Exercise 2

Implement the $PoolGraph$ type which will store our $G(V;E)$ of pools. The set $V$ of vertices will be the pools while the set $E$ of edges will contains a edge between any two pools that have a common token. For example, suppose you have two pools $P_{A,B},P_{B,C}$, where $A,B,C$ are tokens then there will be an edge between them because they share token $B$.

The $PoolGraph$ will be used to generate all the paths going from any token $A$ to any token $B$ so you can already use that information in your implementation, however path generation will be the subject of next week's challenge.

We propose to implement the following methods

- add_pool(pool) // add a pool in the PoolGraph
- routes(from, to) -> RouteGraph // will be implemented next week

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Exercise 3

The main loop of our bot will work roughly as follows

1 Every S seconds
2    let pool_updates = "Fetch pool updates"   
3    Insert pool_updates in graph  
4    for (A,B) in token_lists:
5        let arbitrage = find arbitrage opportunity
6        if arbitrage is None goto 4
7        else execute arbitrage

Implement the steps 1-3

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