Compound V3 (compound-v3)

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When to use it

• Each market (a Comet) has one base asset you can supply for interest or borrow, and a list of collateral assets you supply to borrow it. The namespace names each Comet by its base asset (CUSDCv3, CWETHv3).
• Choose it when you only need to borrow the base asset; for several borrowable assets against shared collateral, Aave V3.

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Pitfalls for a program

• Approve the Comet before supply.
• supply(asset, amount) credits its caller, the Pot: the position is then the Pot’s, not the user’s wallet’s. supplyTo(dst, asset, amount) credits dst; choose which, passing the wallet as a main parameter for dst.
• Supplying the base asset while you have a borrow repays the borrow first.
• Withdrawing more base asset than you supplied borrows the rest, if your collateral allows: check balanceOf and borrowBalanceOf before and after.
• Collateral earns no interest, and each collateral asset has a supply cap.
• balanceOf is the base supply with interest: it grows on its own.

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In a Sauce program

function main(onBehalfOf: Address, amount: Uint256) {
  const before = CompoundV3.CUSDCv3.balanceOf(onBehalfOf);
  USDC.approve(CompoundV3.CUSDCv3, amount);
  CompoundV3.CUSDCv3.supplyTo(onBehalfOf, USDC, amount);
  require(CompoundV3.CUSDCv3.balanceOf(onBehalfOf) > before, "supply not credited");
}

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Notes

• No separate borrow function — withdrawing more base than supplied automatically borrows
• Each Comet market has ONE base asset (e.g. USDC) and multiple collateral assets
• No interest rate mode selection — all borrows are variable rate
• Supply/withdraw of collateral does not earn interest, only the base asset earns
• Market names indicate the base asset: cUSDCv3 = USDC base, cWETHv3 = WETH base
• All supply operations require ERC-20 approval to the Comet address

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Its names in a program

function main() {
  // Ethereum's cUSDCv3, `0xc3d688B66703497DAA19211EEdff47f25384cdc3`.
  require(CompoundV3.CUSDCv3 != 0);
}

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Deployments

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ABI

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CometABI

• supply(address asset, uint256 amount)
• supplyTo(address dst, address asset, uint256 amount)
• withdraw(address asset, uint256 amount)
• withdrawTo(address to, address asset, uint256 amount)
• balanceOf(address account) view returns (uint256)
• borrowBalanceOf(address account) view returns (uint256)

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Next steps

• Protocols: the other protocols, by what they do.
• Protocols and tokens: calling a contract by its namespace, or through its ABI.
• Glossary: the words these pages use, in plain terms.