I didn’t find one in Pervasives, and having read this thread I see why and that there probably is not one.
However, I wanted to do something like initialize an array of (0..9) and figured that identity is more convenient than (fun i -> i).
Raphael explained that it can be found here in Batteries Included.
(via ocaml-beginners)
The current version of Batteries – AAA, on Github – has this in its Pervasives module, so ‘open Batteries’ is all you need. See:
http://thelema.github.com/AAA-batteries/hdoc/BatPervasives.html#VALidentity