[Haskell-cafe] Re: New Hackage category: Error Handling

Ben Franksen ben.franksen at online.de
Sun Dec 6 22:30:34 EST 2009

Michael Snoyman wrote:
> On Sun, Dec 6, 2009 at 12:55 AM, Henning Thielemann <
> lemming at henning-thielemann.de> wrote:
>> On Sun, 6 Dec 2009, Michael Snoyman wrote:
>>  I think there are plenty of examples like web servers. A text editor
>>  with
>>> plugins? I
>>> don't want to lose three hours worth of work just because some plugin
>>> wasn't written
>>> correctly. For many classes of programs, the distinction between error
>>> and exception is
>>> not only blurred, it's fully irrelevant. Harping on people every time
>>> they use error in
>>> the "wrong" sense seems unhelpful.
>>> Hope my commenting on this subject doesn't become my own form of
>>> *pedantry*.
>> In an earlier thread I have explained that one can consider a software
>> architecture as divided into levels. What is an error in one level (text
>> editor plugin, web server thread, operating system process) is an
>> exception in the next higher level (text editor, web server, shell
>> respectively). This doesn't reduce the importance to distinguish between
>> errors and exceptions within one level. All approaches so far that I have
>> seen in Haskell just mix exceptions and errors in an arbitrary way.
> I think we can all appreciate why it would be a bad thing is we treat
> exceptions as errors. For example, I don't want my program to crash on a
> file not found.
> On the other hand, what's so bad about treating errors as exceptions? If
> instead of the program crashing on an array-out-of-bound or pattern-match
> it throws an exception which can be caught, so what?

The error gets hidden instead of fixed?


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