On Jan 23, 2008 5:19 AM, Yitzchak Gale
Those are asynchronous phenomena.
I'm not sure what you mean by that? It's a synchronous exception.
Sorry. I meant external. In the following sense:
The semantics of the program explicitly involve it in a larger external system, in a way that it might make sense to allow exceptions to propagate out to the external system.
With readline history, it is clear that we must handle all conditions internally, so this condition is not met. Since E1-3 are also not met, we should not throw IO exceptions.
-Yitz
The deadline for comments has passed and it seems like there isn't any opposition to adding this to the library. The only thing that remains is to make a decision on the exceptions vs. IO Bool thing. It seems like most are in favor of throwing an exception. For instances where an exception would be too intrusive, I don't see how it would be too hard to write a wrapper function that would have exactly the same monad requirements as the original function but return an IO Bool instead of an error, e.g.
tryReadHistory = catch readHistory (\e -> ...
So where do we go from here? Alex