#ifdef considered harmful (was: DData)

[Sven Panne]

Graham Klyne wrote:
> At 16:12 06/04/04 +0100, Malcolm Wallace wrote:
>> Much as we all hate cpp, I'm afraid the standard libraries are
>> already heavily littered with #ifdefs.  Getting rid of them is
>> basically impossible.
> I guess it's the community's choice of what is important, but in my 
> experience this is a major impediment to distributing portable programs 
> written in Haskell for use by non-Haskellite end users.

Malcolm only pointed out that it is basically impossible to *implement* the
libraries without #ifdefs due to the different capabilities and internal
design choices of the Haskell systems. *Using* these libraries should of
course be possible without reverting to CPP.

>> There should be no externally visible type differences in standard
>> libraries. [...]
> So I would hope, but I seem to recall coming across some variations of 
> function parameters between systems.  I don't remember where.

That shouldn't be the case. I guess we still have some dark corners in the
POSIX vs. non-POSIX area, suggestions for improving this (and other places,
too, of course) are highly welcome. It would really be helpful to know what
caused your grief...

Cheers,
    S.