Hi again.
So, when using GC's FFI backend, it generates two source files for you (and some header files) - in your case, GCTest.hs and GCTest_stub.c. To achieve linker happiness, you need to compile up the latter and include it on the link line *and* drop StdDIS.o from that link line.
Thanks for that - I've achieved linker happiness. FYI, I notice that the GCTest stub file has a do..while(0), which I suppose should be optimised away by GCC, but still makes the code less palatable: -------------------------------------------------------- /* Auto generated GreenCard 2 code for FFI */ double prim_my_sin(double arg1) { double res1; do { res1=sin(arg1); return((double)(res1));} while(0); } -------------------------------------------------------- Cheers Mike Thomas