Uniswap v4 Core repo

Uniswap v4 Core is the draft code repository for Uniswap v4, a new automated market maker protocol with extensible, customizable pools, released so the protocol can be built in public with community feedback. The repo's README says the project is expected to be a months-long process and that any contribution is welcome. All pool state is managed in the PoolManager.sol contract, and integrators call unlock, then implement unlockCallback to run actions such as swap, modifyLiquidity and donate. Pools can be initialized with a hook contract, and the set of callbacks executed on a pool cannot change after initialization.