What elegant and Turing-complete machines* you know? Is there a one from The Book?

Question

Lambda calculus of course is quite elegant, but doesn't it bother you that there is this asymmetry between input and output of a function? I.e. you can make the function take two parameters (by returning a function) but you can't make it return two values. I don't think we could find it in The Book.

Answer 1

You can make it return a function whose evaluations return two values.