Standardized flash loan interface.

While flash loans implementations are nearly all the same, the explicit usage and interface vary.

In this section we cover the flash laons provided by

• Balancer V2 and Swaap
• Aave V2 & V3
• Morpho Blue

Flash loan

The following parameters need to be provided for Aave V2, V3 and Morpho Blue:

The way how the end data is structured is based on the validation logic. Since flash loans use callbacks, we need poolId to validate that the callback was triggred by a trusted Aave or Morpho pool.

params is a packed set of composer operations.

Note that

• The composer re-enters itself here
• The caller address is forwarderd from the origninal call source
• The validation logic is hard-coded, as such, only a limited set of pools are allowed to be called.
• Some flash loan sources are DEXs - e.g. Balancer V2 - this means that swaps thorugh it are not possible any longer as the DEX is typically re-entrancy protected. This also applies to Uniswap V4.

They can be used as follows for e.g. looping USDC in a Aaave type lender.

// select 1M USDC
uint128 amount = uint128(1000000.0e6);

bytes memory innerOperation = abi.encodePacked(
    encodeDeposit(...,USDC, amount,...) // deposit USDC amount to lender
    encodeBorrow(...,USDC, amount,...) // borrow USDC amount from lender
)

bytes memory operation = abi.encodePacked(
    uint8(ComposerCommands.FLASH_LOAN), // then just continue the next one
    uint8(FlashLoanIds.MORPHO_BLUE),
    USDC,
    MORPHO_BLUE_ADDRESS
    amount,
    uint16(innerOperation.length + 1),
    uint8(0), // the original morpho blue has poolId 0.
    innerOperation
)

composer.deltaCompose(operation);