[Haskell-cafe] broken IO support in uvector package, when using non primitive types

Don Stewart dons at galois.com
Fri Mar 13 17:08:13 EDT 2009


UIO's also only a truly alpha idea as a proxy for bytestring/Binary
support.

Patches welcome.

pumpkingod:
> As far as I know, the reason for this is that the UIO instance for
> productions writes the two "rows" out sequentially to file, but
> doesn't include any means to determine the length of the two halves
> when it's loading up again. When you try to read the production back
> in, it tries to read in two arrays, but the first array read consumes
> all the input leaving the second with nothing.
> 
> Having said that, I'm not sure why it used to work. I remember testing
> this on the version in hackage and finding the same issue.
> 
> Cheers,
> Dan
> 
> On Fri, Mar 13, 2009 at 4:46 PM, Daniel Fischer
> <daniel.is.fischer at web.de> wrote:
> > Am Freitag, 13. März 2009 21:18 schrieb Manlio Perillo:
> >> Hi.
> >>
> >> I'm sure this is a know bug, but I can't find details with Google.
> >>
> >> The offending code is here:
> >> http://hpaste.org/fastcgi/hpaste.fcgi/view?id=2362
> >>
> >> When I execute the program I get:
> >>    uio: readChunkBU: can't read
> >>
> >> What's the problem?
> >>
> >>
> >> I'm using uvector from:
> >> http://code.haskell.org/~dons/code/uvector/
> >>
> >>
> >>
> >> Thanks   Manlio Perillo
> >>
> >
> > Worked with uvector-0.1.0.1:
> >
> > $ ghc --make readUArr.hs
> > [1 of 1] Compiling Main             ( readUArr.hs, readUArr.o )
> > Linking readUArr ...
> > $ ./readUArr
> > 2
> >
> > But not with uvector-0.2
> > $ ./readUArr
> > readUArr: readChunkBU: can't read
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