RE: FFI: calling Haskell from C++?

There's been a bit of traffic about calling Haskell from C++ recently, and I know that calling C++ from Haskell is a frequently asked question. (E.g. Koen Claessen was asking me about it this week.) It also seems to be somewhat platform dependent. (Esp on Windows, I think.) Would someone like to write up a description of how to successfully call out from Haskell to C++ and vice versa, using GHC? If you did, we'd gladly include the result in the user manual, and save others a lot of head scratching. Maybe there are simple things we could do to GHC to make the process simpler. But what it needs is someone who knows C++ well to write a coherent story. Please! Simon ________________________________ From: glasgow-haskell-users-bounces@haskell.org [mailto:glasgow-haskell-users-bounces@haskell.org] On Behalf Of Rich Neswold Sent: 13 September 2005 16:45 To: Felix Breuer Cc: glasgow-haskell-users@haskell.org Subject: Re: FFI: calling Haskell from C++? On 9/13/05, Felix Breuer wrote: $ ghc -fffi Foo.o Foo_stub.o main.cpp main.o(.text+0x22): In function `main': main.cpp: undefined reference to `__stginit_Foo()' main.o(.eh_frame+0x11): undefined reference to `__gxx_personality_v0' collect2: ld returned 1 exit status In main.cpp, you need to define __stginit_Foo(void) like this: extern "C" void __stginit_Foo(void); Specifying the "C" linkage with prevent the compiler from looking for a name-mangled version of the function. To fix the second problem, you need to shut off exception handling (specifying the -fno-exceptions option ought to do this. I don't know how to pass compiler option via ghc, though. -- Rich AIM : rnezzy ICQ : 174908475