Sam Steingold <sds@gnu.org> writes:
> I want to modify the _current_ datum in Hashtable.iter, e.g., increment
> a count. Is this code valid?
> Hashtable.iter ht ~f:(fun ~key ~data ->
>   Hashtable.replace ht ~key ~data:(data+1))

If you have associate several datums with the same key, the semantic of the
code is to substitute the current binding of each key with the value of its
earliest binding plus one.

-- 
Zheng Li
http://www.pps.jussieu.fr/~li