Solidity

Good Websites

Good articles:

https://jtriley.substack.com/p/ethereum-virtual-machine-language

7/11/2023

This just launched: https://github.com/pcaversaccio/createx/discussions

About to dive in, but seems like a big deal!

8/11/2023

Another interesting thing I found: https://jtriley.substack.com/p/the-edge-programming-language?r=1qyfrf&utm_campaign=post&utm_medium=web

Building Pristine - a Bitcoin backed stablecoin

Summary

Pristine is a protocol that allows users to deposit Bitcoin and borrow a stablecoin (called Satoshi), against the deposited Bitcoin. For a more detailed description of the protocol, see the github repo.

Things to consider

What happens after a user opens and closes a position? Is the users position deleted from storage? - Currently every address can only open a position once, after that, they can only alter that position, either by depositing, withdrawing, borrowing or repaying.

How do liquidations work? - No fancy auctions, when a users position is between 110% and 100% collateralizes, anyone can pay all their debt and receive their collateral.

Main functions

function open(uint256 _amount) public returns (uint256) {
    if (UserPosition[msg.sender] != 0)
        revert CannotCreateMultiplePositions();
    WBTC.transferFrom(msg.sender, address(this), _amount);
    positionCounter++;
    Positions[positionCounter] = Position(
        msg.sender,
        positionCounter,
        _amount,
        0
    );
    UserPosition[msg.sender] = positionCounter;
    emit Opened(positionCounter, msg.sender, _amount);

    return positionCounter; 
}

function deposit(uint256 _amount, uint256 _id) public PositionExists(_id) {
    WBTC.transferFrom(msg.sender, address(this), _amount);
    Positions[_id].collatAmount += _amount;
    
    emit Deposited(_id, _amount);
}
    

function withdraw(uint256 _amount, uint256 _id) public PositionExists(_id) {
    WBTC.transfer(msg.sender, _amount);
    Positions[_id].collatAmount -= _amount;
    if (!checkPositionHealth(_id)) revert PositionNotHealthy(_id);
    
    emit Withdrew(_id, _amount);
}
    

function borrow(uint256 _amount, uint256 _id) public PositionExists(_id) {
    Satoshi.mint(msg.sender, _amount);
    Positions[_id].borrowedAmount += _amount;
    if (!checkPositionHealth(_id)) revert PositionNotHealthy(_id);
    
    emit Borrowed(_id, _amount);
}

function repay(uint256 _amount, uint256 _id) public PositionExists(_id) {
    Satoshi.burn(msg.sender, _amount);
    Positions[_id].borrowedAmount -= _amount;
    
    emit Repayed(_id, _amount);
}

function liquidatePosition(uint256 _id) public PositionExists(_id) {
    if (checkPositionHealth(_id)) revert PositionHealthy(_id);
    Position memory position = Positions[_id];
    Satoshi.burn(msg.sender, position.borrowedAmount);
    WBTC.transfer(msg.sender, position.collatAmount);
    
    //Update Positions
    delete Positions[_id];
    delete UserPosition[position.owner];
    
    emit Liquidated(_id, position.collatAmount);
}

function redeem(uint256 _id, uint256 _amount) public PositionExists(_id) {
    Satoshi.burn(msg.sender, _amount);
    
    uint256 btcPrice = getCollatPrice();
    uint256 redemptionRate = getRedemptionRate(_id); // Get the redemption rate based on the collateral ratio
    
    uint256 redeemableBTC = (((_amount * redemptionRate) / 10 ** 12) / btcPrice);
    
    // Ensure the position has enough collateral for the redemption
    Position memory position = Positions[_id];
    if (position.collatAmount < redeemableBTC) revert NotEnoughCollateral();
    if (position.borrowedAmount < _amount) revert NotEnoughDebt();
    
    position.collatAmount -= redeemableBTC;
    position.borrowedAmount -= _amount;
    Positions[_id] = position;
    
    WBTC.transfer(msg.sender, redeemableBTC);
    
    emit Redeemed(_id, msg.sender, _amount);
}