Hi there,

Foreign.LowLevel.call has the following type:

Foreign.LowLevel.call;

val it = fn: LowLevel.cType list -> LowLevel.cType -> LowLevel.symbol -> LowLevel.Memory.voidStar * LowLevel.Memory.voidStar -> unit

I understood what the arguments are: the cType list is the type of arguments, the cType is the return type, the symbol is the C function symbol in the loaded library. But the two general pointers are not clear. Where should they point to? For a void argument function I gave

val monitorVoidStar = Foreign.System.loadLibrary "monitor.dll";

for both and it worked, but I guess one of them should be a pointer to the argument list. What is the meaning of these two pointers?

val monitorLib = Foreign.loadLibrary "monitor.dll";

val monitorVoidStar = Foreign.System.loadLibrary "monitor.dll";

fun main () = Foreign.LowLevel.call [] Foreign.LowLevel.cTypeVoid (Foreign.getSymbol monitorLib "say_hello") (monitorVoidStar, monitorVoidStar)

$ cat monitor.c #include <stdio.h>

void say_hello() {

printf("Hello from C!\n");

}

- Gergely