Statically link C++ library with a Haskell library

Question

Setup: I have a Haskell library HLib which makes calls to a C/C++ backend CLib for efficiency. The backend is small and specialized for use with

Answer 1

GHC cannot really understand C++ header files. It needs pure C code. The common way for a C++ header file to provide C interface is to isolate away C++ parts with #ifdef __cplusplus, e.g.:

#ifdef __cplusplus
extern "C" {         // C compilers and various C-based FFIs don't like this
#endif

void foo();

#ifdef __cplusplus
}
#endif

In addition, GHCi is historically known to have problems with linking C++ code. For example, at one point it didn't understand weak symbols (often produced by the compiler in conjunction with inline functions and template instantiations). You might be seeing one of these problems. I'd recommend filing a bug report to the GHC team.