According to https://github.com/ethereum/wiki/wiki/Ethereum-Contract-ABI, function selector is hashed from function name and list of its arguments put inside ().

For example, with function deposit(uint value), the function selector is Keccak hash of string deposit(uint256)

However, it is not clear in the case of constructor & fallback functions: what should be strings - to be hashed - for below 2 cases?

constructor(address addr) public { }

function () payable public { }

Thanks.