Hi,

> Why not have different object types for each of the story types? e.g.

Yes, other people have suggested the same, and while not a perfect
solution (because of the reduplication of fields), the object subtyping
feature of OCaml (the bit that smells a lot like duck-typing...)
is powerful enough to avoid the code duplication in functions such
as print_metadata.  More important, it avoids the ugly hackery with
option types.


> If on the other hand you wanted to ditch objects entirely, you could
> do a similar thing using modules and functors.  E.g.:

That is actually an interesting approach.  If I'm not mistaken, the
semantics for the parameter to a functor is "a module whose signature
contains at least this", which is again similar to duck-typing...

Cheers,
Dario





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