19/01/15 12:19, David Matthews wrote:
On 19/01/2015 04:34, David Topham wrote:Thanks David for your response.While searching I found this comment you made earlier: "The foreign-function interface allows for call-back functions so there is the mechanism to produce a C function that when called calls an ML function." in http://stackoverflow.com/questions/17580386/shared-libraries-in-poly-ml Doesn't this indicate a mechanism that allows an SML function to be called from C?Yes, but the "main program" still has to be in ML. You can call C library functions and pass an ML function as an argument.
Or the ML functions can be passed via global variables that are initialized from the ML side - see attached example. That may be easier if there are a large number of ML functions.
Actually, I did wonder whether this could be used as a way of exporting ML functions to create a library that could be called from a C main program and came to the conclusion that it was going to be too complicated. Poly/ML uses libffi to interface with C. libffi can build closures that wrap around ML functions so that these can be passed into C. The format of the closure it constructs differs markedly depending on the particular architecture since different architectures have different calling conventions for C. The closure is a data structure with pointers in it. Exporting it would require turning the pointers into relocations that the linker/loader will understand. libffi simply doesn't provide that information. It's there by implication in the source code but not explicitly. David _______________________________________________ polyml mailing list polyml@inf.ed.ac.uk http://lists.inf.ed.ac.uk/mailman/listinfo/polyml
call_c_test_10.tar.gz
Description: GNU Zip compressed data
_______________________________________________ polyml mailing list polyml@inf.ed.ac.uk http://lists.inf.ed.ac.uk/mailman/listinfo/polyml
