[Haskell-cafe] No Enum for (,), no Enum or Bounded for Either

[Tom Ellis]

I'm a bit surprised that whilst `Either` and `(,)` have instances for `Ord`

* `(,)` has no instance for `Enum`
* `Either` has no instance for `Enum` or `Bounded`

Is there a particular reason for that?  It might be tricky to implement

    toEnum :: Int -> a
    fromEnum :: a -> Int

but in the presence of `Bounded` that should be possible.

Tom