| It does prompt a question: how does a humble user like myself
| find out that things like toInt shouldn't be used and that
| the correct approach is to use fromIntegral?
With some difficulty. You're suffering from using a tool that evolved
at the leading edge of GHC's development, and therefore initially used
things that hadn't fully 'settled'. We've added a DEPRECATED pragma
to GHC to help warn when you are using things that are going away,
but it's not used everywhere yet. That's not very satisfactory for you,
but it's a consequence of the finite-effort problem.
Simon
