Using DeepSeq for exception ordering

[Antoine Latter]

Is this related to imprecise exceptions?

http://research.microsoft.com/en-us/um/people/simonpj/papers/imprecise-exn.htm

Antoine


On Thu, Nov 8, 2012 at 12:01 PM, Nicolas Frisby <nicolas.frisby at gmail.com>wrote:

> And the important observation is: all of them throw A if interpreted in
> ghci or compiled without -O, right?
>
>
> On Thu, Nov 8, 2012 at 11:24 AM, Albert Y. C. Lai <trebla at vex.net> wrote:
>
>> On 12-11-08 07:12 AM, Simon Hengel wrote:
>>
>>> I was just going to say that I can give at least one counterexample
>>> where this does not hold:
>>>
>>>    evaluate (('a' : undefined) `deepseq` return () :: IO ())
>>>    throwIO exceptionB
>>>
>>> But then I realized that here exceptionA is optimized away altogether.
>>> For me this smells like a bug.  Is this related to [1]?
>>>
>>> [1] http://hackage.haskell.org/**trac/ghc/ticket/2273<http://hackage.haskell.org/trac/ghc/ticket/2273>
>>>
>>
>> Interesting. A few more tests (all GHC 7.4.2, linux, x86 32-bit, use "ghc
>> -O" to compile):
>>
>> The following cases throw A:
>>
>> import Control.DeepSeq
>> import Control.Exception
>>
>> main = do
>>   evaluate (('a' : error "A") `deepseq` return () :: Maybe ())
>>   throwIO (userError "B")
>>
>> main = do
>>   evaluate (('a' : error "A") `deepseq` ())
>>   throwIO (userError "B")
>>
>> main = do
>>   evaluate (('a' : error "A") `deepseq` True)
>>   throwIO (userError "B")
>>
>> main = do
>>   x <- evaluate (('a' : error "A") `deepseq` putStrLn "hi")
>>   x
>>   throwIO (userError "B")
>>
>> The following cases throw B:
>>
>> main = do
>>   evaluate (('a' : error "A") `deepseq` return () :: IO ())
>>   throwIO (userError "B")
>>
>> main = do
>>   evaluate (('a' : error "A") `deepseq` putStrLn "hi")
>>   throwIO (userError "B")
>>
>> main = do
>>   evaluate (('a' : error "A") `deepseq` getLine)
>>   throwIO (userError "B")
>>
>>
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>
>
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