There's no doubt that Hugs could produce better error messages in this
situation and perhaps offer some advice to the user. But I don't
think it would be wise to treat these top-level expressions
differently from those in scripts. If the user types in [], should
Hugs print [] or ""? Without invoking some sort of defaulting not
specified in the report, you can't know. If the user types
(reverse "") should the system print []? That's confusing too.
Problems with a missing "deriving Show" don't bother me: the error is
easily understood and corrected. It would bother me if code that
works fine from the command line didn't typecheck in a program.
I'm not saying these are real concerns; I just think the issue here is
better error messages rather than any sort of semantic change in Hugs.
John
