Format Vyper Code¶

Moccasin provides a format command that allows you to automatically format your Vyper code. This feature requires the mamushi tool to be installed.

1. Prerequisites¶

Before using the format command, you need to install mamushi. We recommend using uv for installation:

uv tool install mamushi

Alternatively, you can install it with pip:

pip install mamushi

2. Basic usage¶

To format a single Vyper file:

mox format contracts/MyContract.vy

To format all Vyper files in your project:

mox format contracts/

3. Format specific files¶

Format a single contract:

mox format contracts/Token.vy

Format multiple specific files:

mox format contracts/Token.vy contracts/Vault.vy

Format all files in a directory:

mox format contracts/

4. Integration with project workflow¶

The format command works seamlessly with your moccasin project structure:

my_project/
├── moccasin.toml
├── contracts/
│   ├── Token.vy
│   ├── Vault.vy
│   └── interfaces/
│       └── IERC20.vy
└── scripts/
    └── deploy.py

Format all contracts:

mox format contracts/

Format contracts and interfaces:

mox format contracts/ contracts/interfaces/

5. Formatting standards¶

The mamushi formatter applies consistent styling to your Vyper code, including:

Consistent indentation
Proper spacing around operators
Standardized line breaks
Uniform comment formatting

6. Before and after example¶

Before formatting:

#pragma version ^0.4.0

@external
def transfer(to:address,amount:uint256)->bool:
    assert to!=empty(address)
    self.balances[msg.sender]-=amount
    self.balances[to]+=amount
    return True

After formatting:

# pragma version ^0.4.0

@external
def transfer(to: address, amount: uint256) -> bool:
    assert to != empty(address)
    self.balances[msg.sender] -= amount
    self.balances[to] += amount
    return True

7. Integration with development workflow¶

Consider integrating the format command into your development workflow:

Pre-commit formatting:

# Format all contracts before committing
mox format contracts/ && git add contracts/

Continuous formatting during development:

# Format and compile in one go
mox format contracts/ && mox compile