Exceptions vs. Errors (Re: Readline read_history and write_history addition)

[Isaac Dupree]

>> It should really be:
>>
>> block x = do
>>   IO blockAsyncExceptions#
>>   ret <- x
>>   IO unblockAsyncExceptions#
>>   return ret
>>
>> in which case we could then supply implementations for
>> other monads as well.
> 
> blockAsyncExceptions# has some tricks to restore tail-recursion in some 
> cases (see the paper).  But apart from losing that optimisation, I can't 
> think of any reasons why the above couldn't work - one thing you have to 
> worry about is what happens when x raises an exeption, but I think that 
> is handled by the way we save and restore the blocked state in catch.

what about if the monad is a transformed one with its own error handling 
methods (e.g. ErrorT IO) and so (IO blockAsyncExceptions#) is run but 
(IO unblockAsyncExceptions#) is not? Is that a problem?

~Isaac