Proposal: Extensible exceptions

David Menendez dave at
Sun Jul 6 17:31:34 EDT 2008

On Sun, Jul 6, 2008 at 4:31 PM, Henning Thielemann
<lemming at> wrote:
> On Sun, 6 Jul 2008, David Menendez wrote:
>>> data DivideByZero = DivideByZero deriving (Show, Typeable)
> Maybe I annoy you with my distinction of errors and exceptions, but I
> consider DivideByZero a bad example for an exception, because it is more an
> error (I see it is used in the extensible exception paper anyway).

It's also in the current Control.Exception library.

While dividing by zero or accessing an array out of bounds isn't the
same as a file not existing, I'm not sure we need different mechanisms
for dealing with them. If your code divides by zero, you still want
any "finally" or "bracket" clauses to get called before the program

Dave Menendez <dave at>

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