Singleton Flash Loan Interface

Operations → Flash Loans → Singletons (Composer)

Lead type: ComposerCommands.GEN_2025_SINGELTONS.

The singleton flash loans are constructed from atomic operations on values, e.g., the Balancer V3 vault and Uniswap V4 Position Manager.

Supported Providers

Balancer V3

Balancer V3 provides flash loans through its vault contract with advanced features:

• Lead Command: ComposerCommands.GEN_2025_SINGELTONS
• Sub-type: DexForkMappings.BALANCER_V3

Uniswap V4

Uniswap V4 provides flash loans through its position manager:

• Lead Command: ComposerCommands.GEN_2025_SINGELTONS
• Sub-type: DexForkMappings.UNISWAP_V4

Parameter Structure

Offset	Length (bytes)	Type	Description
0	20	address	Asset contract address to borrow
20	32	uint256	Amount to borrow (in asset decimals)
52	Dynamic	bytes	Packed composer operations to execute

Solidity Example: Balancer V3 Flash Loan

// Inner operations to execute during flash loan
bytes memory innerOperations = abi.encodePacked(
    uint8(ComposerCommands.TRANSFERS),
    uint8(0), // Transfer type
    address(this), // recipient
    amount // amount to transfer
);
// Main flash loan operation
bytes memory operation = abi.encodePacked(
    uint8(ComposerCommands.GEN_2025_SINGELTONS),
    uint8(DexForkMappings.BALANCER_V3),
    BALANCER_V3_VAULT,
    USDC, // asset to borrow
    amount, // amount to borrow
    innerOperations // operations to execute
);
// Execute the flash loan
composer.deltaCompose(operation);

TypeScript Example (using viem)

export function encodeBalancerV3FlashLoan(composerAddress: `0x${string}`, amount: bigint): `0x${string}` {
    // Inner operations to execute during flash loan
    const innerOperations = encodePacked(
        ["uint8", "uint8", "address", "uint256"],
        [
            ComposerCommands.TRANSFERS,
            0, // Transfer type
            "0x...", // recipient address
            amount,
        ]
    )

    // Main flash loan operation
    const operation = encodePacked(
        [
            "uint8", // ComposerCommands.GEN_2025_SINGELTONS
            "uint8", // DexForkMappings.BALANCER_V3
            "address", // vault address
            "address", // asset
            "uint256", // amount
            "bytes", // inner operations
        ],
        [ComposerCommands.GEN_2025_SINGELTONS, DexForkMappings.BALANCER_V3, BALANCER_V3_VAULT, USDC_ADDRESS, amount, innerOperations]
    )

    return operation
}

// Usage example
const operationData = encodeBalancerV3FlashLoan(
    "0x...", // composer address
    1000000n
)

// Call the composer
await publicClient.writeContract({
    address: composerAddress,
    abi: parseAbi(["function deltaCompose(bytes data)"]),
    functionName: "deltaCompose",
    args: [operationData],
})