ERC-2212 v2 - HackMD

ERC-2212 v2 === ``` eip: 2212 title: ERC-2212 Interest Earning Stakes author: Paul Razvan Berg (@PaulRBerg) <hello@paulrberg.com> discussions-to: https://github.com/ethereum/EIPs/issues/2212 status: Draft type: Standards Track category: ERC created: 2019-07-30 requires: 20 ```  ## Simple Summary  We propose a new way to monetise decentralised apps that involves users staking tokens in exchange for a product or a service and creators earning interest on the pooled stakes through a continuous lending protocol such as [Compound](https://compound.finance). ## Abstract  The advent of decentralised lending brought to the web3 ecosystem a new primitive for designing business models. We herein describe a smart contract interface that accepts deposits ("stakes") in ERC20 tokens. These deposits are immediately lent on the market to earn interest either for just the owner of the contract, or for both them and the user. We assume that users get access to a product or a service for as long as they keep staking tokens. ## Motivation  While most web3 business models rely on paying a percentage fee on transfers, or commiting to a monthly subscription, we aim to flip the model on its head. Users are their own banks now, so, instead of charging them, we make them stake tokens that can be claimed back, in full, at any point in time. We view this as a win-win-win scenario for users, dapp creators and lending protocols. It is worth it to mention PoolTogether, a "no-loss lottery" that launched recently. It works by having participants deposit money in their contracts, locking it up for a while and earning interest through Compound. Ultimately, they choose a lucky winner and return the deposits back to all other players. PoolTogether takes a 10% commission on the prize. We wrote this specification because interest earning stakes are a powerful financial instrument and a community-vetted standard and implementation will reduce the cost of replication. ### Use Cases - Software products and services - Charity pools - Games - Gym memberships ## Specification  Having an owner is mandatory for this spec to make sense, thus we assume that a proper implementation would use a well-known contract such as OpenZeppelin's [Ownable](https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/ownership/Ownable.sol). For brevity, we haven't included any method for assigning or transferring ownership. ### Methods #### owner Returns the owner of the contract. ```solidity function owner() external view returns (address); ``` #### fee Returns the fee as a percentage value scaled by 1e18. ```solidity function fee() external view returns (uint256); ``` #### balanceOf Returns the stake that consists of the initial deposit plus the interest accrued over time. SHOULD revert if `staker` doesn't have an active stake. ```solidity function balanceOf(address staker) external view returns (uint256); ``` #### depositOf Returns the initial deposit. SHOULD revert if `staker` doesn't have an active stake. ```solidity function depositOf(address staker) external view returns (uint256); ``` #### stake Creates a new stake object for `msg.sender`. Automatically converts an underlying to its lending form so that the contract can earn interest. MUST revert if `msg.sender` already has an active stake. **Triggers Event**: [Stake](#stake) ```solidity function stake(address tokenAddress, uint256 amount) external; ``` #### redeem Returns the deposit plus any accrued interest to the staker and levies the fee for the `owner`. MUST revert if `msg.sender` is not the staker or the owner. **Triggers Event**: [Redeem](#redeem) ```solidity function redeem(address staker) external; ``` #### takeEarnings Withdraws the earnings accrued over time. MUST revert if `msg.sender` is not the owner. **Triggers Event**: [TakeEarnings](#take-earnings) ```solidity function takeEarnings(address tokenAddress, uint256 amount) external; ``` #### updateFee Updates the fee practiced by the contract. Has to be a percentage value scaled by 1e18. Can be anything between 0% and 100%. MUST revert if `msg.sender` is not the owner. **Triggers Event**: [UpdateFee](#update-fee) ```solidity function updateFee(uint256 newFee) external; ``` --- ### Events #### Stake MUST be triggered when `stake` is successfully called. ```solidity event Stake(address indexed staker, address indexed underlyingAddress, bool converted, uint256 deposit, uint256 exchangeRate); ``` #### Redeem MUST be triggered when `redeem` is successfully called. ```solidity event Redeem(address indexed staker, address indexed underlyingAddress, uint256 fee, uint256 withdrawal); ``` #### TakeEarnings MUST be triggered when `takeEarnings` is successfully called. ```solidity event TakeEarnings(address indexed tokenAddress, uint256 indexed amount); ``` #### UpdateFee MUST be triggered when `updateFee` is successfully called. ```solidity event UpdateFee(uint256 indexed fee); ``` ## Rationale  In the v1 of this spec, there were a few methods highly specific to Compound: - whitelistCToken(address, address) - discardCToken(address, address) - resetAllowance(address, address) We removed them to make the spec protocol agnostic. It is up to the implementor if they choose Compound, Maker or they roll out their own lending market. Finally, we designed these interest earning stakes with simplicity in mind, while acknowledging that there are some missing features and obvious concerns which we shall discuss below. --- ### Missing Features #### Update By and large, this is the most prominent missing feature. Dapp creators might want to update their staking requirements and the only way to achieve that would be to ask users to redeem their previous stake and put in the new amount. We assume that most apps don't need this and the spec as it is now is sufficient for running the very first experiments. Yet, time will tell best. We are looking forward to making updates if need be. #### Parallel Staking Large enterprises have multiple sources of revenue, hence swiching to a business model based on staking would require a smart contract that accepts multiple stakes per user. However, the goal is to avoid writing an over-optimised standard. Parallel staking would require dapp creators to keep track of multiple stake ids, instead of only the user's account. Also, the user's interface would become more complex, as they would have to be aware of multiple stakes. --- ### Concerns #### Loan Defaults Lending never comes without risks, so interest earning stakes are not a good fit for the ultra-sensitive business applications. That said, dapp creators have an incentive to monitor the market for borrowers that go under the collateral requirements and liquidate them. By doing so, they secure the network for their own users and also earn a fee in the process. #### Fluctuating Rates The market rates for lending stablecoins hovered around 10% in early 2019, but this is not a given. Dapp creators can accommodate this issue by asking for a stake that generates interest reasonably above what they deem as an acceptable revenue stream. #### Rent-Seeking Interest earning stakes work best for products or services that are priced on time instead of quantity (imagine subscription-based SaaS). If a dapp is quota-based, its creators would be better off charging a fee on every transfer. ## Implementation  [Head to the Sablier organisation on GitHub](https://github.com/SablierApp/ies) for a WIP implementation. ## Additional References - [Thread on cTokens](https://twitter.com/PaulRBerg/status/1147980107740524544) - [Compound Presidio](https://compound.finance/developers) - [PoolTogether](https://pooltogether.us) - [Pooled cDAI](https://github.com/ZeframLou/pooled-cdai) - [Lending Proxy by Luciano Bertenasco](https://github.com/lbertenasco/lending-proxy) - [Web3 Revenue Primitives](https://github.com/FEMBusinessModelsRing/web3_revenue_primitives) ## Copyright Copyright and related rights waived via [CC0](https://creativecommons.org/publicdomain/zero/1.0/). @PaulRBerg and @SablierHQ ✌️

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