hweak is an hastable with weak pointer enabling the GC to collect thing
that are in the hashtable.

Weak_memo.c is an object that contain object of some class type, and
give them back (with the same class type) when given the very same
object with a different type (that is coerced to some other class type).

You could use it to make some kind of upcast. Of course, an object is
not prevented to be collected by the GC if he is in a Weak_memo.c object

To install : do make, copy the *.cmo and *.cmi where you need them.

Distribution under the terms of the GNU Library General Public License,
with the special exception on linking described in the LICENCE file of
the Objective Caml distribution          

documentation can be build by « make doc », and is in the doc
directories


You need ocaml 3.06 for this to work.