Check
(fix F (A B : Set) (f : A -> B) (l : list A) {struct l} :
list B := match l with
| nil => nil
| a :: l => f a :: F _ _ f l
end).
(* V8 printing of this term used to failed in V8.0 and V8.0pl1 (cf BZ#860) *)
Check
let fix f (m : nat) : nat :=
match m with
| O => 0
| S m' => f m'
end
in f 0.
Open Scope Z_scope.
Inductive even: Z -> Prop :=
| even_base: even 0
| even_succ: forall n, odd (n - 1) -> even n
with odd: Z -> Prop :=
| odd_succ: forall n, even (n - 1) -> odd n.
(* Check printing of fix *)
Ltac f id1 id2 := fix id1 2 with (id2 n (H:odd n) {struct H} : n >= 1).
Print Ltac f.

(* Incidentally check use of fix in proofs *)
Lemma even_pos_odd_pos: forall n, even n -> n >= 0.