> Could anyone tell me whether the feature of polymorphic
> recursion is available in Caml-light or OCaml? If so,

Basically, the answer is no for the Caml-light or O'Caml
systems. Plans to add some form of polymorphic recursion is on the way.

For more details, have a look in the archive of this mailing list:

http://pauillac.inria.fr/caml/caml-list/subject.html

Subject: polymorphic recursion

Best regards,

Pierre Weis

INRIA, Projet Cristal, Pierre.Weis@inria.fr, http://cristal.inria.fr/~weis/