W liście z pią, 25-06-2004, godz. 12:30 +0200, Daan Leijen napisał(a):
> It seems to me that returning the old value is always good
> enough right? Here is an implementation of "atomicModifyIORef"
> with the current type in terms of a function "proposedModifyIORef" with
> type (2).
>
> atomicModifyIORef :: IORef a -> (a -> (a,b)) -> IO b
> atomicModifyIORef ref f
> = do old <- proposedModifyIORef ref (fst . f)
> return (snd (f old))
It applies f twice, which may duplicate work.
--
__("< Marcin Kowalczyk
\__/ [EMAIL PROTECTED]
^^ http://qrnik.knm.org.pl/~qrczak/
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