[Haskell-cafe] An exceptional exception

[Andrew Coppin]

I've been doing some testing to try to figure out the tangled maze that 
is exception handling. (Is there a *reason* why half of all exceptions 
are dynamic, and the other half aren't? Couldn't we have just 1 system?)

Anyway, I wrote a cute little "test" function for figuring out how each 
kind of exception works:

 > test (fail "go away")
isAlreadyExistsError=False
isDoesNotExistError=False
isAlreadyInUseError=False
isFullError=False
isEOFError=False
isIllegalOperation=False
isPermissionError=False
isUserError=True

Next I tried this:

 > test (getDirectoryContents "banana")
isAlreadyExistsError=False
isDoesNotExistError=True
isAlreadyInUseError=False
isFullError=False
isEOFError=False
isIllegalOperation=False
isPermissionError=False
isUserError=False


And now, this:

 > test (writeFile "C:\\C:\\x" "test")
isAlreadyExistsError=False
isDoesNotExistError=False
isAlreadyInUseError=False
isFullError=False
isEOFError=False
isIllegalOperation=False
isPermissionError=False
isUserError=False

Erm... so this exception registers as "False" on every single predicate?

How exactly am I meant to detect this error?