The bitSize typeclass method has been deprecated since 4.7. However, library author still have to implement it to avoid a warning. I propose that a default implementation using bitSizeMaybe be added. It would look like this:

bitSize x = case bitSizeMaybe x of

Nothing -> error "bitSize is deprecated and the type in question does not have a finite bit size"

Just a -> a

-Andrew Thaddeus Martin