> Since the Report states that the derived Show instances only insert
> parentheses where needed and that the derived Read instances can
> read the output produced by show, I would suggest to change all
> occurences of {showsPrec 10,readsPrec 10} to {showsPrec 0,readsPrec 0}
> in the above code.
That seems like a reasonable suggestion, but it doesn't fix the bug.
Regards,
Malcolm