> I saw some messages about external structure (such "large array") and
> interfaces with ocaml.
> With the function alloc_final, we can give the free function of the
> external type to GC.
> I think the other interesting feature to use in ocaml is marshalling
> (perhaps there are others).
> Do you think it is possible to give, like the free function, the
> marshall function for an external type ?

Yes, we have some work in progress in this direction.  The idea is
to attach to "finalized" blocks a record of C functions, supporting
not only finalization, but also equality test, hashing, marshalling
and unmarshalling.  This would be useful not only for large arrays,
but also for other datatypes in the Caml library such as big integers.

- Xavier Leroy