Just a thought, but what are the ramifications of taking the other route, relaxing the haskell 98 spec to allow implementations to expand the set of valid exceptions? a function can be used to determine whether it is something not covered by the haskell 98 spec (even if we dont know anything else about it..) and we can at least rethrow it or 'show' it in logs or whatever. lots of useful little functions can be written which are haskell 98 but should be general enough to handle random exceptions, it would be silly to have to keep 2 versions around... <snip>
It's difficult to "relax the Haskell 98 spec" in this way, since most compilers can be used in a strict Haskell 98 mode. Up to now this hasn't required using a different set of libraries, but if -fglasgow-exts changed the meaning of IO.catch then it would. Instead, I'd suggest deprecating System.IO.catch and perhaps the rest of the IOError support in System.IO. It is all available from System.IO.Error and Control.Exception anyhow. Cheers, Simon