[swiftcoder]

With respect, I think that's moving the goalposts. If we have defined out of existence all forms of I/O, then what are we actually discussing?

[steveklabnik]

We haven't, that's why Turing completeness is not relevant for the question at hand.

I can implement the non-IO parts of Brainfuck with safe Rust, so it is Turing Complete. That doesn't change the fact that there are useful programs not expressible in it.