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Hifi SDK

The Hifi SDK is structured as a collection of small and medium-sized node packages. These packages contain both Solidity and JavaScript code. The former is the smart contracts themselves; the latter, the smart contract ABIs and the TypeChain bindings.

There are a couple of things you need to keep in mind regarding the Hifi SDK:

  1. The Solidity contracts can be compiled only with Solidity v0.8.4 and above, because we are reverting with custom errors instead of reason strings.
  2. It depends upon ethers.js. You cannot use the SDK with another JavaScript library like web3.js.
caution

The latest version of the SDK is used in production in the Hifi Interface, but it is considered alpha software and may contain bugs or change significantly between patch versions. If you have questions about how to use the SDK, please reach out in the #development channel of the Discord. Pull requests welcome!

Protocol

The core Hifi fixed-rate, fixed-term lending protocol.

Installation

$ yarn add @hifi/protocol

Usage

Solidity

// SPDX-License-Identifier: Unlicense
pragma solidity >=0.8.4;

import "@hifi/protocol/contracts/core/balanceSheet/IBalanceSheetV1.sol";

contract YourContract {
// Find the address on https://docs.hifi.finance
IBalanceSheetV1 balanceSheet = IBalanceSheetV1(0x...);

function queryAccountLiquidity(address user) external view returns (uint256 excessLiquidity, shortfallLiquidity) {
(excessLiquidity, shortfallLiquidity) = balanceSheet.getCurrentAccountLiquidity(user);
}

function queryCollateralAmount(address user, IErc20 collateral) external view returns (uint256 collateralAmount) {
debtAmount = balanceSheet.getCollateralAmount(user, collateral);
}

function queryDebtAmount(address user, IHToken hToken) external view returns (uint256 debtAmount) {
debtAmount = balanceSheet.getDebtAmount(user, hToken);
}
}

JavaScript

import { getDefaultProvider } from "@ethersproject/providers";
import { BalanceSheetV1__factory } from "@hifi/protocol/dist/types/factories/BalanceSheet__factory";

async function queryAccountLiquidity() {
const balanceSheetABI = BalanceSheetV1__factory.abi;
const defaultProvider = getDefaultProvider();
const balanceSheet = new BalanceSheetV1__factory("0x...", defaultProvider); // Find the address on https://docs.hifi.finance
const user = "0x...";
const accountLiquidity = await balanceSheet.getCurrentAccountLiquidity(user);
}

AMM

Dedicated AMM for market-making hTokens, based on the Yield Space design.

Installation

$ yarn add @hifi/amm

Usage

Solidity

// SPDX-License-Identifier: Unlicense
pragma solidity >=0.8.4;

import "@hifi/amm/contracts/IHifiPool.sol";

contract YourContract {
// Find the address on https://docs.hifi.finance
IHifiPool hifiPool = IHifiPool(0x...);

function getQuote(uint256 hTokenIn) external view returns (uint256 underlyingOut) {
underlyingOut = hifiPool.getQuoteForSellingHToken(hTokenIn);
}
}

JavaScript

import { parseUnits } from "@ethersproject/units";
import { getDefaultProvider } from "@ethersproject/providers";
import { HifiPool__factory } from "@hifi/amm/dist/types/factories/HifiPool__factory";

async function getQuote() {
const hifiPoolABI = HifiPool__factory.abi;
const defaultProvider = getDefaultProvider();
const hifiPool = new HifiPool__factory("0x...", defaultProvider); // Find the address on https://docs.hifi.finance
const hTokenIn = parseUnits("100", 18);
const underlyingOut = await hifiPool.getQuoteForSellingHToken(hTokenIn);
}

Proxy Target

DSProxy target contract with stateless scripts. Refer to the technical reference for more details about DSProxy.

Installation

$ yarn add @hifi/proxy-target

Usage

Solidity

You will likely never need to interact with the smart contracts from Solidity. Though for the sake of completeness, here is a code snippet for how to do that:

// SPDX-License-Identifier: Unlicense
pragma solidity >=0.8.4;

import "@hifi/proxy-target/contracts/IHifiProxyTarget.sol";

contract YourContract {
// Find the address on https://docs.hifi.finance
IHifiPool hifiProxyTarget = IHifiProxyTarget(0x...);

function depositCollateral(IBalanceSheetV1 balanceSheet, IErc20 collateral, uint256 depositAmount)
external
view
returns (uint256 underlyingOut)
{
hifiProxyTarget.depositCollateral(balanceSheet, collateral, depositAmount);
}
}

JavaScript

This code snippet shows how to interact with a DSProxy contract that is already deployed. For guidance on how to deploy the DSProxy itself, refer to Maker's guide Working with DSProxy.

import { parseUnits } from "@ethersproject/units";
import { HifiProxyTarget__factory } from "@hifi/protocol/dist/types/factories/HifiProxyTarget__factory";

async function depositCollateral() {
const hifiProxyTargetABI = HifiProxyTarget__factory.abi;
const signer = "..."; // Get hold of an ethers.js Signer
const hifiProxyTarget = new HifiProxyTarget__factory("0x...", signer); // Find the address on https://docs.hifi.finance
const balanceSheet = "0x...";
const collateral = "0x...";
const depositAmount = parseUnits("100", 18);
const accountLiquidity = await hifiProxyTarget.depositCollateral(balanceSheet, collateral, depositAmount);
}

Flash Swap

Flash swap implementations for liquidating underwater accounts. We can currently source liquidity only from Uniswap V2 and its forks.

Installation

$ yarn add @hifi/flash-swap

Usage

Solidity

You are not supposed to import the smart contracts. Instead, you should interact with the Uniswap pool directly. For example, with the UniswapV2Pair contract you would call the swap function, and then Uniswap will forward the call to the FlashUniswapV2 contract. You can read more about flash swaps work in Uniswap on docs.uniswap.org.

JavaScript

Example for Uniswap V2:

import { defaultAbiCoder } from "@ethersproject/abi";
import { getDefaultProvider } from "@ethersproject/providers";
import { parseUnits } from "@ethersproject/units";
import { UniswapV2Pair__factory } from "@hifi/flash-swap/dist/types/factories/UniswapV2Pair__factory";

async function flashSwap() {
const defaultProvider = getDefaultProvider();
const pair = new UniswapV2Pair__factory("0x...", defaultProvider);

const token0Amount = parseUnits("100", 18);
const token1Amount = parseUnits("0", 18);
const to = "0x..."; // Address of FlashUniswapV2, get it from https://docs.hifi.finance

const borrower = "0x...";
const hToken = "0x...";
const turnout = parseUnits("1", 18);
const data = defaultAbiCoder.encode(["address", "address", "uint256"], [borrower, hToken, turnout]);

await pair.swap(token0Amount, token1Amount, to, data);
}