Extensible Exceptions and IO

Ian Lynagh igloo at earth.li
Sat May 23 12:09:49 EDT 2009

On Sat, Apr 25, 2009 at 11:18:43AM -0700, Alexander Dunlap wrote:
> In the extensible exceptions paper[1], which I believe is the guide
> behind the current Control.Exception in GHC 6.10, a SomeIOException
> type is discussed so that it would be possible to use the nice
> interface for IOExceptions. Is this implemented anywhere? In the GHC
> libraries, all I see is the old interface just plugged into a simple
> wrapper, so you have to use guard . isDoesNotExistError (for example)
> with catchJust to catch a certain type of exception. If not, are there
> any plans to implement it?

I'm not aware of anyone currently working on putting the various core
libs' exceptions into a sensible hierarchy, but it would be great if
someone was to do so!

I'd suggest that the best way to do this would be initially a
combination of discussions on the mailing list (if anything is
non-obvious) and building a design (and, if appropriate, rationale) on a
wiki page, and ending with a library submissions proposal once you have
a design worked out:



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