On Fri, Nov 14, 2003 at 01:57:41PM +1100, Manuel M T Chakravarty wrote:

...

These marshalling routines convert Haskell's Unicode representation for characters into the platform-specific encoding used for \code{wchar\_t} and vice versa. In particular, on platforms that represent \code{wchar\_t} values according to the encoding specified by ISO/IEC 10646, this conversion reduces to a simple type cast without any alteration of the character values. For all other platforms, the exact rules of the conversion are platform-specific and not further defined in this report.

Does anybody have any suggestions for improving this explanation?

I don't think we need to say anything special, the conversion to wchar_t * is just as defined as that to char *. it is a locale dependent operation just like withCString and friends. one would make their decision as to which to use based on the library they are trying to bind too, if a wchar_t interface is supported it should be prefered because it is more likely to preserve character codes.

It is true that strictly speaking we don't need to say anything here. But I think it would be helpful to include a footnote as a guide to implementors, something along the lines of [1] Note that if the platform defines __STDC_ISO_10646__ then wchar_t characters are Unicode code points, and thus the conversion between Haskell Char and CWChar is a simple cast. On other platforms, the translation is locale-dependent just as for CChar. And the paragraph in question could be just The module \code{CString} also exports a variant of the above string marshalling routines for wide characters, i.e. the C \code{wchar_t} type[1]. Cheers, Simon