(** Building with possible sharing using a iterator [g] : We now suppose in addition that [f n] is in fact the [n]-th iterate of a function [g]. *)
Hypothesis Hg_correct: forall n, f (S n) = g (f n).
CoFixpoint imemo_make (fn:A) : Stream A :=
let fn1 := g fn in
Cons fn1 (imemo_make fn1).
Definition imemo_list := let f0 := f 0 in
Cons f0 (imemo_make f0).

Theorem imemo_get_correct: forall n, memo_get n imemo_list = f n.
End MemoFunction.