[ Non-Hugs-specific stuff follows ... ]
Apart from the fact that Hugs98 still doesn't implement hSeek,
there seems to be some argument confusion:
-- iomonad.c ---------------------------------------------------------
[...]
primFun(primHSetPosn) {
#if HAVE_FSETPOS
fpos_t pos = 0;
#elif HAVE_FSEEK
long pos = 0;
#endif
Int h;
HandleArg(h,3);
IntArg(pos,4);
[...]
----------------------------------------------------------------------
This probably corresponds to
hSetPosn :: Handle -> HandlePosn -> IO ()
and not the required
hSetPosn :: HandlePosn -> IO ()
Consequently, I always get an "Illegal operation" here.
This bug leads to something in the Haskell 98 library report I
haven't really understood yet (section 11.5):
* Why are there *two* ways to reposition a handle (one via
hSeek and the other one via hSetPosn)?
* Where is hTell?
* Why is the handle supposed to be contained in HandlePosn?
This way one can't keep "a finger" within a file without keeping
it open. Yes, I know that the file can change in the meantime,
but this is not under Haskell's control, anyway.
Because it's already too late for Haskell 98, I propose the following
for Haskell 2000:
Keep hSeek as it is, remove HandlePosn/hGetPosn/hSetPosn and add
hTell :: Handle -> IO Integer
Rationale: Keeping a file position opaque is a bad idea, because
*lots* of file formats rely on the fact that arithmetic is possible
on file positions, see e.g. http://www.wotsit.org/. Merging a file
position with a handle is even worse, because this keeps the file
open even when only the position is needed later.
Opinions?
Cheers,
Sven
--
Sven Panne Tel.: +49/89/2178-2235
LMU, Institut fuer Informatik FAX : +49/89/2178-2211
LFE Programmier- und Modellierungssprachen Oettingenstr. 67
mailto:[EMAIL PROTECTED] D-80538 Muenchen
http://www.informatik.uni-muenchen.de/~Sven.Panne
