[Haskell-cafe] what is f=f (not) doing ?

Bulat Ziganshin bulat.ziganshin at gmail.com
Sun Sep 23 06:58:45 EDT 2007


Hello Lennart,

Sunday, September 23, 2007, 2:05:46 PM, you wrote:

i bet that general case contains too much conditions to check. program
may be unblocked by other thread, by OS signal, by I/O operation
completion, by C thread. how for example RTS can check that we have
started I/O operation with completion callback which will call abort()
function?

> I agree.  This situation is totally detectable.

> On 9/23/07, Neil Mitchell <ndmitchell at gmail.com> wrote: 
> Hi

>> I'm not sure, but since it would require the detection of an evaluation
 >> that does not terminate,  it comes down to the halting problem, which is
>> not generally solvable. Maybe the experts can confirm my intuition?

> I think your intuition is off. This isn't the problem of detecting 
> that a computation might not halt, its a question of detecting after
> the fact a very restricted case of non-termination has occurred. I
> think it should be possible to assign threads etc to these things, but
> may make the code run slower in the common case. 

> Thanks

> Neil
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>   


-- 
Best regards,
 Bulat                            mailto:Bulat.Ziganshin at gmail.com



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