[ColonelPhantom]

Hm yeah, I'm not sure what astrange's point was, other than probably dissatisfaction with the combination of exceptions and Either (which I think is awfully named, as it implies a certain 'equality' between l and r).

I haven't used Bluefin, but don't Bluefin exceptions suffer from the same issue where it, essentially, 'infects' the program flow? For example, `fst (5, error "second")` seems like it would translate to `fst $ (5,) <$> throw e "second"`, where you would also need to pull an `e` from somewhere. More realistic, something like head would probably be quite awkward:

head e [] = throw e "head: empty list" head e (x:xs) = pure x

You now need to pass in the exception handle, and the return value is now `Eff es a` instead of `a`. This means that you cannot just use the result, so you will likely need to fill your program with monadic stuff like do-notation, <$> and <$>, complicating the program flow and likely also reducing laziness.

[tome]

You're right, but my response would be that

    fst (5, error "second")

and

    head [] = error "empty list"
    head (x:xs) = x

are simply not things you should be writing. They're not good program design and it's not a weakness that Bluefin doesn't support them unaltered.