[Haskell-cafe] Use unsafePerformIO to catch Exception?
xj2106 at columbia.edu
Mon Mar 23 08:11:47 EDT 2009
I just feel it is not comfortable to deal with exceptions
only within IO monad, so I defined
> tryArith :: a -> Either ArithException a
> tryArith = unsafePerformIO . try . evaluate
and it works quite good as
> map (tryArith . (div 5)) [2,1,0,5]
> [Right 2,Right 5,Left divide by zero,Right 1]
However, I guess unsafePerformIO definitely has a reason for
its name. As I read through the document in
System.IO.Unsafe, I can't convince myself whether the use of
'tryArith' is indeed safe or unsafe.
I know there have been a lot of discussion around
unsafePerformIO, but I still can't figure it out by myself.
Can someone share some thoughts on this particular use of
unsafePerformIO? Is it safe or not? And why?
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