let
  curried_add be (x:int) => (y:int) => x+y
in
  let fib2 be
   (* Given n>0, returns the pair containing fib(n) and fib(n-1)
    *)
    rec g(n:int):int*int =>
         (n == 1) ? (1,1) :
            let p be g(n-1) 
            in let n1 be (fst p)
               in let n2 be (snd p)
                  in
                    (n2, curried_add n1 n2)
  in
    let fib be
         (n:int) =>  (n == 0) ? 1 : (snd (fib2(n-1)))
    in
      fib 6