[Haskell-cafe] Re: Hugs vs GHC (again) was: Re: Somerandomnewbiequestions

Simon Marlow simonmar at microsoft.com
Tue Jan 11 07:39:09 EST 2005

On 11 January 2005 11:39, Marcin 'Qrczak' Kowalczyk wrote:

> Ben Rudiak-Gould <Benjamin.Rudiak-Gould at cl.cam.ac.uk> writes:
>>     http://www.haskell.org/~simonmar/io/System.IO.html
> "fileRead :: File -> FileOffset -> Integer -> Buffer -> IO ()"
> This is unimplementable safely if the descriptor is read concurrently
> by different processes. The current position is shared.

There's a big lock on File.  If you want to do truly concurrent reading,
you can make multiple FileInputStreams, each of which has its own file
descriptor (the Unix implementation uses dup(2)).


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