On Wed, Feb 22, 2012 at 3:05 PM, Evan Laforge
It's awkward and surprising how getEnv throws an exception when an env var is not set, since it's very common for env vars to be optional, and it's not convenient to catch exceptions in haskell (I have to look up Control.Exception every time, and then add LANGUAGE
For true IO exceptions, you should be using the Prelude.catch mechanism. It's the right thing to do and makes your program more portable as a bonus. It is quite unfortunate that IO exceptions became conflated with imprecise and dynamic exceptions and clash in their names. They really are different beasts alltogether. In particular, IO can be fully understood via the following desugaring. data IO a = IO (State -> (State,Either IOException a)) imprecise exceptions break this cognitive desugaring and cause odd things like throwIO and raise having slightly different and confusing syntax and APIs being unclear on what they mean by 'exception'. In any case, they will definitely be completely different beasts in jhc if I decide to implement imprecise exceptions. John