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: http://www.haskell.org/haskellwiki/Library_submissions Thanks Ian