Zero's behavior is totally consistent with the other numbers, though - it doesn't break associativity, commutativity, or any of the other stuff you'd expect. On

Zero's behavior is totally consistent with the other numbers, though - it doesn't break associativity, commutativity, or any of the other stuff you'd expect. On the other hand, NULL takes every type I've ever written and adds an instance whose behavior with every function is, at best, to crash my program, and at worst, completely undefined. Its behavior is not at all consistent with the other instances.