ft-burn?

Function Signature

(ft-burn? token-name amount sender)

• Input:
  • token-name: The name of the fungible token
  • amount: The amount of tokens to burn (uint)
  • sender: The principal from whose balance the tokens will be burned
• Output: (response bool uint)

Why it matters

The ft-burn? function is crucial for:

1. Decreasing the total supply of a fungible token.
2. Implementing token burning mechanisms in tokenomics models.
3. Allowing users to destroy their own tokens.
4. Managing token supply in deflationary token systems.

When to use it

Use ft-burn? when you need to:

• Implement a token burning feature in your contract.
• Reduce the circulating supply of a token.
• Allow users to voluntarily destroy their tokens.
• Execute deflationary mechanisms in your token economy.

Best Practices

• Ensure that the sender has sufficient balance before attempting to burn.
• Use ft-burn? in conjunction with proper access controls.
• Consider emitting events or logging burns for transparency.
• Be cautious when burning tokens from a different principal than tx-sender.

Practical Example: Token Burning Mechanism

Let's implement a simple token burning function:

(define-fungible-token cBtc)

(define-data-var tokenAdmin principal tx-sender)

(define-public (burn-tokens (amount uint))
  (ft-burn? cBtc amount tx-sender)
)

(define-public (burn-tokens-from (amount uint) (owner principal))
  (begin
    (asserts! (is-eq tx-sender (var-get tokenAdmin)) (err u3))
    (ft-burn? cBtc amount owner)
  )
)

This example demonstrates:

1. Using ft-burn? to burn tokens from the transaction sender.
2. Implementing an admin function to burn tokens from any account.
3. Using assertions to ensure only the admin can burn tokens from other accounts.

Common Pitfalls

1. Attempting to burn more tokens than the sender has in their balance.
2. Not checking the return value of ft-burn? to handle potential errors.
3. Allowing unauthorized burning of tokens from other accounts.
4. Forgetting that burned tokens are permanently destroyed and cannot be recovered.

Related Functions

• ft-mint?: Used to create new tokens, increasing the total supply.
• ft-transfer?: Used to transfer tokens between principals.
• ft-get-balance: Used to check the token balance of a principal.
• ft-get-supply: Used to get the current total supply of tokens.

Conclusion

The ft-burn? function is a powerful tool for managing the supply of fungible tokens in Clarity smart contracts. It allows for the implementation of deflationary mechanisms and gives users the ability to destroy their own tokens. When used correctly, it can be a key component in sophisticated tokenomics models. However, it should be used with caution and with proper checks to ensure the integrity of your token system.