[MLton] array flattening
Fri, 9 Jul 2004 10:07:58 -0700
> Oh yes.. please document a magic prim/type con. so the programmer can be
> guaranteed that The array flatter won't "do the wrong thing".
> type 'a boxed
> val box: 'a -> 'a boxed
> val unbox : 'a boxed -> 'a
This seems quite reasonable, and fairly easy to implement. I'd
certainly go for the primitive type (not the datatype).
> While, we are on the subject
> type 'a ext_rep
> val toExtRep: 'a -> 'a ext_rep
> val fromExtRep: 'a ext_rep -> 'a
> where "ext_rep" means external representation. i.e. tell MLton to turn off
> all data representations for this type.
I don't like this at all. There is no such thing as a standard
representation for SML types. We've exposed a few representations for
our FFI, but exposing more will just tie our hands and make the
whole system and user code more brittle.
> So I can portably access the structure via C or some other evil FFI.
The right way to do this is to use our existing _export mechanism to
export accessor functions. That way, MLton, and only MLton, knows all
the representation stuff, and speaks the standard C FFI that other
systems already know.