[MLton-user] Calling C functions with a variable number of arguments

[John Reppy]

We support varargs in SML/NJ using a technique described in a 2008 ML Workshop
paper.  A key feature of our approach is that it should be possible to use our
implementation in any ML system that supports C calls.  You can find a copy of
the paper at

	http://people.cs.uchicago.edu/~jhr/papers/2008/ml-varargs.pdf

On Jul 26, 2010, at 2:00 PM, mlton-user-request at mlton.org wrote:
> 
> Hi,
> 
> I have been using the FFI and have found it very flexible but have 
> run 
> into a problem that I can't see how to solve.  I am trying to call a 
> C 
> function with a variable number of arguments but need the variability 
> in 
> the number of arguments available in SML too.
> 
> The attached examples show that there is no problem importing a C 
> function with a variable argument list for a fixed number of 
> arguments: 
> the files 'call_sum_<N>.sml' import the C function 'sum' with N 
> arguments for the variable argument list.  I need to do something like
> 
>   val sum = _import "sum" : int * int list -> int;
> 
> (I am happy for the variable arguments to have the same type in SML.)
> Does anyone have any ideas about how to achieve a similar effect?
> 
> Thanks,
> Phil