[Haskell-cafe] Opening the same file multiple times

[Einar Karttunen]

On 11.12 22:26, Donn Cave wrote:
> Quoth Einar Karttunen <ekarttun at cs.helsinki.fi>:
> | It seems that opening the same file multiple times (one writer
> | and multiple readers) is not supported at least on *nix with
> | GHC. I want to use one Handle to use append data till the
> | end of the file while other Handles perform random access
> | IO with seeks on the file.
> 
> How is it not supported?  What happens with something like this

Try the same in ghc / ghci:

e at yui:~$ ghci
   ___         ___ _
  / _ \ /\  /\/ __(_)
 / /_\// /_/ / /  | |      GHC Interactive, version 6.4.1, for Haskell 98.
/ /_\\/ __  / /___| |      http://www.haskell.org/ghc/
\____/\/ /_/\____/|_|      Type :? for help.

Loading package base-1.0 ... linking ... done.
Prelude> :m IO
Prelude IO>         af <- openFile "z" AppendMode
Prelude IO>         sf <- openFile "z" ReadMode
*** Exception: z: openFile: resource busy (file is locked)
Prelude IO> 

- Einar Karttunen