> | Finally, I tried maxBound::Integer, and I don't understand why I get
> | *this* error message:
> |
> | Prelude> maxBound::Integer
> | ERROR: Unresolved overloading
> | *** type : Bounded Integer => Integer
> | *** expression : maxBound
> |
> | Oh, but I just saw that it's the same with 1.3c, so this is not a bug,
> | just something to work on...
>
> Can you clarify what you mean here? I don't see whay you would expect
> us to be working on. The error message is different from the one that
> you would have seen in previous releases of 1.4 ("Integer is not an
> instance of Bounded"); the new message says the same thing, plus more,
> because it also gives some context, like the part of the type to the
> right of the => symbol. The inferred type "Bounded Integer => Integer"
> means that, if the constraint (Bounded Integer) were satisfied, then
> maxBound::Integer would return an integer. But alas, the overloading
> cannot be resolved because the constraint cannot be solved, so an
> error is reported. This is a very simple example, of course. In
> practice, the types involved could be more complex, and might even
> involve multiple parameter classes. That's why a more informative
> error message is needed.
I always thought that resolving in this context means figure out what
a type (constructor) variable means, and Bounded Integer => Integer
clearly has none. So indeed I expected something like "not an instance
of", but I guess I can get used to understanding "Unresolved
overloading" instead. Showing the infered type is definitely a good
idea.
Christian Sievers
