[Haskell-cafe] Automatic file closing after readFile

[Magnus Therning]

On Thu, Oct 18, 2007 at 09:25:32 -0400, David Roundy wrote:
>On Thu, Oct 18, 2007 at 01:16:37PM +0100, Magnus Therning wrote:
>> On Thu, Oct 18, 2007 at 20:58:45 +1000, Matthew Brecknell wrote:
>> >For a less hackish solution, you need to do a bit more work. Again, this
>> >is untested.
>> >
>> >> loadAndCheck fn = bracket (openFile fn ReadMode) hClose checkContents
>> >> checkContents fh = do { s <- hGetContents fh; return $! hasEmpty s }
>> >
>> >Note the explicit close, and "return $!" to ensure that hasEmpty has
>> >done its work before the file is closed.
>> 
>> Ah, `bracket` is a handy function to know!
>
>Note that you almost never want to use the bracket defined in Haskell98,
>nor the one in IO.Error.  You want the bracket defined in
>Control.Exception.

Yes, thankfully that's documented in the Haddock for the only one that
turns up on Hoogle.

/M

-- 
Magnus Therning                             (OpenPGP: 0xAB4DFBA4)
magnus＠therning．org             Jabber: magnus．therning＠gmail．com
http://therning.org/magnus
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