Fuses

Fuses are one of three pillars on which Fusion stands. Fuses are the remedy providing permissionlessness, transparency, security, and speed of development.

All Fuses must meet the following requirements:

• Stateless — They have no memory, no configuration, and they store no data. Thanks to that they can be used by multiple vaults at the same time without the risk of interfering with one another.

• Non-upgradable — Fuses, by nature, are simple contracts that can not be altered. That assures a Plasma Vault’s actions can be trusted and Fuses can be shared without additional risk. Should the destination market’s ABI change, a new Fuse needs to be deployed.*

• Standard ABI — One of the tasks of the Fuse is to bring the interface of the market down to a standard ABI. Fuses implement two core functions: Enter and Exit that, depending on context deploy or withdraw assets, take a loan or repay it, etc. On top of that some Fuses can implement instantWithdraw — a function with predefined params to pull the assets from the market without the need for Alpha’s interaction. This is relevant if the Vault allows for instant redemptions of shares.

• Configurability — Because Fuses are stateless, any configuration is delegated to the vault. The Fuse is built to accept the calls with the configuration.

Types of Fuses

Fuses, by design, are limited to specific uses. One protocol may allow many use cases such as providing liquidity, trading derivatives, staking, etc. Outside of functions that can be performed, there are other kinds of actions that need to be performed such as checking balance or claiming incentives. Below is the detailed list of kinds of fuses used by Fusion.

Functional fuses

These bi-directional fuses allow for action and its reversion. What that means depends on the protocol but some examples would include:

• Provide and withdraw liquidity from a DEX or a Credit Market

• Borrow against collateral and repay the loan

• Open and close a derivative such as an option, an interest rate swap, or a perpetual future

Balance Fuses

Each project may require slightly different steps to price assets that are deposited into it by the vault. Vault may be depositing liquidity and at the same time borrowing against collateral. Balance fuse provides a standard way to account for the balance that is then taken when calculating the exchange of the vault's shares. When supporting a given protocol, a balance fuse is the mandatory fuse to provide.

Rewards Fuses

Each Plasma Vault comes standard with a Rewards module. It is responsible for claiming the rewards on behalf of the Vault and allows to pass the claimed incentives to a dedicated agent for processing. If the rewards are sold, the proceeds can be deposited back to the rewards manager and vested into the vault. More information about this process can be found in the VAULT LINK HERE. Claiming of the rewards is done via a specialized fuse, that when invoked, will handle the logic of claiming the rewards.

Swap Fuses

Swapping in the context of Fusion is not reversible. Therefore the swap fuses have slightly different interfaces. They allow for the swapping of two approved assets. MORE INFORMATION NECESSARY - fuse configuration.

Custom Fuse

Besides the typical fuses listed above, custom fuses can be created and used by the vault. Since fuses follow a delegate call, the fuse custom function can also be executed. This can extend the functionality of the vault to accommodate new workflows. It is important to note that custom fuses must be thoroughly tested, and possibly audited before use.

Developing a Fuse

The IPOR DAO is dedicating efforts to provide lots of quality fuses. However, if you would like to see a fuse developed that is not on the DAO's backlog, you may want to develop it yourself. If you're the protocol administrator and wish Fusion to integrate with you, this is the fastest way to integrate. You can find detailed instructions on the dedicated page.