FFI: calling Haskell from C++?
simonpj at microsoft.com
Wed Sep 14 11:05:26 EDT 2005
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,
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!
From: glasgow-haskell-users-bounces at haskell.org
[mailto:glasgow-haskell-users-bounces at haskell.org] On Behalf Of Rich
Sent: 13 September 2005 16:45
To: Felix Breuer
Cc: glasgow-haskell-users at haskell.org
Subject: Re: FFI: calling Haskell from C++?
On 9/13/05, Felix Breuer <felix at fbreuer.de> 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
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.
AIM : rnezzy
ICQ : 174908475
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