Original bug ID: 1401
Reporter: administrator
Status: closed
Resolution: won't fix
Priority: normal
Severity: feature
Category: ~DO NOT USE (was: OCaml general)

Bug description

Hello!

I have encountered a situtation where the precondition that
two lists be of the same length is too strict. Yet, I must
iterate on the two lists contemporarily. Hence, I would like
to express the wish to extend the standard library List
module with such iterators as the following:

let rec iter2opt (f:'a option -> 'b option -> unit) l1 l2 =
match l1, l2 with
| [], [] -> ()
| h1 :: t1, [] -> f (Some h1) None; string_iter2opt f t1 []
| [], h2 :: t2 -> f None (Some h2); string_iter2opt f [] t2
| h1 :: t1, h2 :: t2 -> f (Some h1) (Some h2);
string_iter2opt f t1 t2

I offer to write them myself, should the Caml team deem such
an addition to the standard library to be useful for everybody.

Alex