Ptr and ForeignPtr Questions

[Ashley Yakeley]

At 2001-09-23 04:04, Marcin 'Qrczak' Kowalczyk wrote:

>It would be impossible then to directly call a C function with a
>parameter declared as a const pointer. It's illegal in C to have
>mismatching prototypes of the same function.

You can always do this:

  module MyModule where
      {
      foreign import StringCopy :: Ptr Int8 -> Ptr Int8 -> IO ();
      }

which autogenerates this header:

  extern "C"
      {
      void MyModule__StringCopy(signed char* a,signed char* b);
      }

which the user can implement like this:

  char* strcat(char* dest, const char* src);

  void MyModule__StringCopy(char* dest,char* src)
      {
      strcat(dest,src);
      }

(assuming char and signed char are identical).


-- 
Ashley Yakeley, Seattle WA