[Haskell-cafe] [Newbie] Cannot derive Eq and Show. Why?
Peter Arrenbrecht
peter.arrenbrecht at gmail.com
Fri Sep 8 10:03:36 EDT 2006
Hi all
I am stumped again. The following code generates the error "ERROR
file:.\Cube.hs:12 - An instance of IArray UArray a is required to derive Eq
(Cube a b)" in Hugs. But I did specify the IArray UArray k constraint. So
what is wrong?
module Cube( Cube(..) )
where
import Data.Array.Unboxed
data (Ord k, IArray UArray k, IArray UArray v) =>
Cube k v
= Empty
| Values (UArray Int k) (UArray Int v)
| Subs (UArray Int k) (Array Int (Cube k v))
deriving (Show, Eq)
Thanks for any help
-peo
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