No, not if you include the state of the world in the type signature. If you make every primitive IO function take a RealWorld value and return one, you can thre

No, not if you include the state of the world in the type signature. If you make every primitive IO function take a RealWorld value and return one, you can thread the execution correctly using the last one as an argument to the next. But then the question is what happens if you reuse a RealWorld that you already called a function with. That leads you to types with values that can only be used once, uniqueness types (https://en.wikipedia.org/wiki/Uniqueness_type https://en.wikipedia.org/wiki/Uniqueness_type). Which is the solution for IO that Clean, the other lazy functional language, uses.