RE: ANN: H98 FFI Addendum 1.0, Release Candidate 13

 
> I have put RC 14 at
> 
>   http://www.cse.unsw.edu.au/~chak/haskell/ffi/
> 
> including all the feedback on RC13.  Please especially have
> a look at Section 6.3 (Section "CString"), where some of the
> wording changed.

The spec is silent on how exactly a Haskell Char is translated to a
CWchar, and there aren't any conversion functions ala castCharToCCHar /
castCCharToChar.

So presumably the expected behaviour is that the implementation does its
best to translate between Unicode Char and whatever encoding the
prevailing C library is using for wchar.  Any sensible implementation
will be using Unicode for wchar too, so the translation will be a simple
no-op, but the C standard doesn't specify this.  Older systems will
probably have a locale-dependent encoding for wchar.  The GNU C library
has a slight bug in this regard, too (see previous discussion).

I expect that when we implement the CWString operations for GHC we won't
bother with any locale-dependent translations, so the implementation
will only work on "sensible" systems.

There is a fair bit that is non-obvious here, so I feel the spec ought
to say something.

Cheers,
	Simon