I think that new SomeAsyncException type in base is supposed to make
it possible to ignore all asynchronous exceptions.
https://github.com/ghc/packages-base/blob/master/GHC/IO/Exception.hs#L113
On Wed, 10 Jul 2013 09:28:12 +0300 Michael Snoyman
There's a pattern that arises fairly often: catching every exception thrown by code. The naive approach is to do something like:
result <- try someCode case result of Left (e :: SomeException) -> putStrLn $ "It failed: " ++ show e Right realValue -> useRealValue
This seems perfectly valid, except that it catches a number of exceptions which seemingly should *not* be caught. In particular, it catches the async exceptions used by both killThread and timeout.
I think it's fair to say that there's not going to be a single function that solves all cases correctly, but it is a common enough situation that people need to write code that resumes work in the case of an exception that I think we need to either have some guidelines for the right approach here, or perhaps even a utility function along the lines of:
shouldBeCaught :: SomeException -> Bool
One first stab at such a function would be to return `False` for AsyncException and Timeout, and `True` for everything else, but I'm not convinced that this is sufficient. Are there any thoughts on the right approach to take here?