Minting & Burning: Token Supply Control

1// Minting: create new tokens
2function _mint(address to, uint256 amount) internal {
3    require(to != address(0), "Mint to zero address");
4
5    _totalSupply += amount;        // Increase total supply
6    _balances[to] += amount;       // Credit the recipient
7
8    emit Transfer(address(0), to, amount); // from = 0x0 signals a mint
9}
10
11// Burning: destroy existing tokens
12function _burn(address from, uint256 amount) internal {
13    require(from != address(0), "Burn from zero address");
14
15    uint256 accountBalance = _balances[from];
16    require(accountBalance >= amount, "Burn exceeds balance");
17
18    _balances[from] = accountBalance - amount;
19    _totalSupply -= amount;
20
21    emit Transfer(from, address(0), amount); // to = 0x0 signals a burn
22}

1// Different minting access control patterns:
2
3// Pattern 1: Only owner can mint (centralized)
4function mint(address to, uint256 amount) external onlyOwner {
5    _mint(to, amount);
6}
7
8// Pattern 2: Role-based (multiple authorized minters)
9function mint(address to, uint256 amount) external onlyRole(MINTER_ROLE) {
10    _mint(to, amount);
11}
12
13// Pattern 3: Proof-based (this dApp's pattern!)
14function completeTask(uint256 taskId, bytes32 nonce, bytes signature) external {
15    require(verifySignature(msg.sender, taskId, nonce, signature));
16    require(!isTaskCompletedBy[msg.sender][taskId], "Already completed");
17    isTaskCompletedBy[msg.sender][taskId] = true;
18    effortToken.mint(msg.sender, tasks[taskId].rewardAmount);
19}
20
21// Pattern 4: Burn is often permissionless
22function burn(uint256 amount) external {
23    _burn(msg.sender, amount);
24}