[Haskell-cafe] RE: Enum class
Arjun Guha
GUHAARJU at grinnell.edu
Sun Jan 9 23:50:11 EST 2005
Sorry, that was a stupid error. I meant to use fromEnum:
> next:: (Enum a, Bounded a) => a -> a
> next v = if (fromEnum v) == (fromEnum maxBound)
> then minBound
> else succ v
I don't think this will quite work if fromEnum:: a -> Int for type a, were not
injective. However, that might be part of the specification... I don't
remember.
It should be fine, so long as the preimage of (fromEnum maxBound) is
{maxBound}.
-Arjun
--
Arjun Guha <guhaarju at grinnell.edu>
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