Ptr and ForeignPtr Questions

Manuel M. T. Chakravarty
Sun, 23 Sep 2001 21:02:14 +1000

Ashley Yakeley <> wrote,

> At 2001-09-23 00:45, Manuel M. T. Chakravarty wrote:
> >No, unfortunately not.  Consider, for example, that storage
> >qualifiers would have to be generated correctly and there is
> >no way to determine form a Haskell type whether a `const'
> >modifier needs to be added.
> I would assume that Ptr types would always be mapped to non-const 
> pointers. Do you have an example of a Haskell type for a foreign import 
> function, for which the corresponding C function type would be ambiguous?

Take, for example, the following excerpt of the Linux man

  STRCAT(3)           Linux Programmer's Manual           STRCAT(3)

	 strcat, strncat - concatenate two strings

	 #include <string.h>

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

	 char *strncat(char *dest, const char *src, size_t n);

If you want to bind these functions from Haskell, you have
to deal with `const' qualifiers.  The same holds for many
other functions in existing C libraries.