Re: nlffi cvt vs get

Quoting brian <briand-/[email protected]>:
> I went back to the "no longer foreign" paper and found the following  
> snippet of example code:
> 
> fun maxx l = let
>    fun x l =
>      C.Cvt.ml_double
>       (C.Get.double
>         (IXDB.S_record.f_x
>           (C.Ptr.|*| l)))
[...]
> The C.Get.double call returns a type which is incompatible with  
> C.Cvt.ml_double

Yes, glancing at the SML/NJ SVN sources, the spec of Cvt.ml_double is

        val ml_double    : double     -> MLRep.Double.real

and Get.double is

        val double    : 'c double_obj     -> MLRep.Double.real

double is an abstract type specified in the C signature

    type [...]    and double

and the C structure is opaquely sealed with the C signature

structure C :> C_INT
(* ... *)
structure C : C = C_Int

thus the type C.double will be a new type.

Apparently parts of NLFFI have changed since the paper was written or the
example in the paper was never compiled.

-Vesa Karvonen

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