I mean, you can have an immutable stateless computer, but it's just called a "boolean logic circuit". You give it an input, it gives you an output, that's all.

I mean, you can have an immutable stateless computer, but it's just called a "boolean logic circuit". You give it an input, it gives you an output, that's all. In practice, you'll of course actually be using a computer with RAM. Most likely, it will even have a Von Neumann architecture. That leaves you open to everything from race conditions to hardware failures to cosmic rays putting a machine into a bad state.