Comparison with False - something I don't understand

Mel mwilson at the-wire.com
Mon Dec 6 08:32:18 EST 2010


Paul Rubin wrote:

> mdw at distorted.org.uk (Mark Wooding) writes:
>> The most obvious improvement is resumable exceptions.
> 
> You know, I've heard the story from language designers several times
> over, that they tried putting resumable exceptions into their languages
> and it turned out to be a big mess, so they went to termination
> exceptions that fixed the issue.  Are there any languages out there with
> resumable exceptions?  Escaping to a debugger doesn't really count as
> that.  I guess one way to do it would be call a coroutine to handle the
> exception, and either continue or unwind after the continue returns, but
> doing it in a single-threaded system just seems full of hazards.

Apparently, at the end of his research, Alan Turing was trying out the idea 
of 'oracles', where a computable process would have access to an 
uncomputable process to get particular results.  I would imagine that the 
idea here was to clarify what this would do to the computable process.  If 
he had lived, I doubt that Turing would have built an oracle, but the idea 
does live on in interactive debuggers.

It would seem if some situation has arisen that can be fixed by code, then 
you can just run that code there and then.  Then 'resumable exceptions' just 
become a kind of subroutine call, perhaps like the triggers in SQL.

	Mel.




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