On 08-Jul-1999, Keith Wansbrough <[EMAIL PROTECTED]> wrote:
>
> > And for other constructor kind, like say, Pair, List ...
> > "deriving" does not seem to make much sense.
> > Because there exist too many equally good ways to `enum' these
> > types. Hence, it is better to leave this for the possible separate
> > user Enum declaration.
>
> Ah, but the same is true for Ord and yet Ord instances may be derived
> automatically. Deriving should do something that is clearly sensible;
> it doesn't have to be the only thing possible. I think the
> lexicographic ordering is clearly sensible.
Can you give some (hopefully compelling) examples of why it would be
useful to have Enum instances for such types?
--
Fergus Henderson <[EMAIL PROTECTED]> | "I have always known that the pursuit
WWW: <http://www.cs.mu.oz.au/~fjh> | of excellence is a lethal habit"
PGP: finger [EMAIL PROTECTED] | -- the last words of T. S. Garp.
