[Haskell-cafe] [Newbie] Cannot derive Eq and Show. Why?

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 -- View this message in context: http://www.nabble.com/-Newbie--Cannot-derive-Eq-and-Show.-Why--tf2239265.htm... Sent from the Haskell - Haskell-Cafe forum at Nabble.com.