[Haskell-cafe] Misleading MVar documentation

[Don Stewart]

ezyang:
> Merry Christmas all!
> 
> Is it just me, or does the Control.Concurrent.MVar documentation seem a bit
> misleading?  In particular, we should explicitly note the race conditions
> for not just swapMVar but also readMVar, withMVar, modifyMVar_ and modifyMVar,
> and clarify that the safety guarantees of the latter three pertain to their
> handling of asynchronous exceptions.
> 
> It might also be good to tell people that if they need race-free operations
> of this style, STM is a good alternative to look at, even if only one variable
> is being synchronized over.
> 

That would be a good contribution.