[Haskell-cafe] lazy strings and parallel read

Duncan Coutts duncan.coutts at worc.ox.ac.uk
Fri Sep 19 13:01:37 EDT 2008


On Fri, 2008-09-19 at 18:46 +0200, Manlio Perillo wrote:
> Don Stewart ha scritto:
> > manlio_perillo:
> >> Hi.
> >>
> >> After having read
> >> http://book.realworldhaskell.org/read/concurrent-and-multicore-programming.html#id676390
> >>
> >> I have a doubt about Data.ByteString.Lazy.
> >>
> >> Why getContents function don't use pread (or an emulation, if not 
> >> available)?
> > 
> > Why would it?
> > 
> 
> So that you don't need to open the same file multiple time:
> http://book.realworldhaskell.org/read/concurrent-and-multicore-programming.html#id677193

We are constrained here by the semantics of Handle which requires
that getContents semi-close the Handle (which in turn is to make it
harder to shoot yourself in the foot while doing lazy IO).

Duncan



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