Uniswap V3

Uniswap V3 ETH/USDC liquidity pool on Arbitrum:

This example tracks the price of the ETH/USDC Uniswap V3 liquidity pool on Arbitrum:

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Which displays prices emitted by the below script:

onBlock(block => {
    for (const rootTx of block.getTransactions()) {
        for (const tx of rootTx.flattenChildren({
            // Arbitrum WETH/USDC liquidity pool
            //   https://www.geckoterminal.com/fr/arbitrum/pools/0xc31e54c7a869b9fcbecc14363cf510d1c41fa443
            contract: '0xc31e54c7a869b9fcbecc14363cf510d1c41fa443',
            // we're only interested in calls, not static calls
            onlyOp: 'CALL',
        })) {
            // get reserves
            const {sqrtPriceX96, x, y, xDec, yDec} = getPriceData(tx.to);

            // compute price, as a numeric value
            //  see https://ethereum.stackexchange.com/questions/98685/computing-the-uniswap-v3-pair-price-from-q64-96-number
            const numerator1 = sqrtPriceX96 * sqrtPriceX96;
            const price = numerator1 * (10n ** 18n) / (2n ** BigInt(96 * 2));
            const p = Number(price) / (10 ** (18 + Number(yDec - xDec)));

            // send !
            emit({
                t: block.timestamp,
                pool: tx.to,
                blockNumber: block.number,
                x,
                y,
                priceXY: p,
                priceYX: 1/p,
            });

            // we dont care if there is more than 1 tx on this block
            return;
        }
    }
})

const {Main:{getPriceData}} = solidity<Pricing>`
pragma solidity ^0.8.15;

// see https://github.com/Uniswap/v3-core/blob/main/contracts/interfaces/IUniswapV3Pool.sol
//    - https://github.com/Uniswap/v3-core/blob/main/contracts/interfaces/pool/IUniswapV3PoolImmutables.sol
//    - https://github.com/Uniswap/v3-core/blob/main/contracts/interfaces/pool/IUniswapV3PoolState.sol
interface IUniswapV3Pair {
    function slot0()
        external
        view
        returns (
            uint160 sqrtPriceX96,
            int24 tick,
            uint16 observationIndex,
            uint16 observationCardinality,
            uint16 observationCardinalityNext,
            uint8 feeProtocol,
            bool unlocked
        );
    function token0() external view returns (address);
    function token1() external view returns (address);
}

interface IERC20 {
    function decimals() external view returns (uint256);
}

contract Main {
    function getPriceData(IUniswapV3Pair pool) public view returns (
        uint160 sqrtPriceX96,
        address x,
        address y,
        uint256 xDec,
        uint256 yDec
    ) {
        (sqrtPriceX96,,,,,,) =  pool.slot0();

        x = pool.token0();
        y = pool.token1();

        xDec = IERC20(x).decimals();
        yDec = IERC20(y).decimals();
    }

}`;