aux []
let rec list_findopt f l =
- let rec aux = function
+ let rec aux k = function
| [] -> None
| x::tl ->
- (match f x with
- | None -> aux tl
+ (match f x k with
+ | None -> aux (succ k) tl
| Some _ as rc -> rc)
in
- aux l
+ aux 0 l
let split_nth n l =
let rec aux acc n l =