Sample code for 'Getting Started with Smart Contracts' talk at geekcamp.sg

SimpleToken.sol

pragma solidity ^0.5.11;

contract SimpleToken {
    string public constant name = "GeekCamp Token";
    string public constant symbol = "GEEK";
    uint8 public constant decimals = 0;
    
    address public minter;
    mapping (address => uint) private _balances;

    constructor() public {
        minter = msg.sender;
    }
    
    function balanceOf(address account) public view returns (uint) {
        return _balances[account];
    }    

    function mint(address to, uint amount) public returns (bool) {
        require(msg.sender == minter);
        require(amount > 0);
        _balances[to] += amount;
        return true;
    }

    function transfer(address to, uint amount) public returns (bool) {
        require(amount <= _balances[msg.sender], "Insufficient balance.");
        _balances[msg.sender] -= amount;
        _balances[to] += amount;
        return true;
    }
}