Hi,

I've updated to the latest version of Sexplib, and the support for hashtable serialisation
seems broken or at least changed.  I was accustomed to using the syntax extension
for convenient declaration of (de)serialisers, and this worked too for the Hashtbl module.
For example:


type dict_t = (key_t, value_t) Hashtbl.t with sexp

But with Sexplib 7.0.4 this produces an error:


Error: Unbound value Hashtbl.t_of_sexp

Is this a bug, or must the (de)serialisers be declared manually with the newer versions
of Sexplib?

Thanks in advance for your time!
Best regards,
Dario Teixeira