Asynchronous exceptions and laziness bugs in
marlowsd at gmail.com
Fri Mar 19 09:53:30 EDT 2010
On 19/03/2010 13:16, Bas van Dijk wrote:
> On Thu, Mar 18, 2010 at 11:45 AM, Simon Marlow<marlowsd at gmail.com> wrote:
>> Thanks, I'm actually going to change this to use STM as it does a better job
>> than MVars in this case.
> Hi Simon, I see you actually write 'val+1' to the MVar:
> newUnique :: IO Unique
> newUnique = atomically $ do
> val<- readTVar uniqSource
> let next = val+1
> writeTVar uniqSource $! val + 1
> return (Unique next)
> Why don't you write 'next' so that when you force the returned Unique
> it doesn't need to be computed a second time?
> (The attached patch fixes it)
Yes, silly mistake. I'll apply your patch, thanks.
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