[Haskell-beginners] Haskell type Array a b

I'm looking on the Haskell 98 Report, and the definition of (==) for values of type Array a b looks wrong to me. Here is the definition given: a == a' = (assocs a == assocs a') But this fails to account for the array length in each dimension; hence, if x is a 0 x 2 array, y is a 2 x 0, and z is a 0 x 0 array, then x == y x == z, and y == z are all True, even though bounds x != bounds y, bounds x != bounds z, and bounds y != bounds z. This violates the most fundamental property of equality: that if a == b, then you can substitute a for b in an expression without changing the value of the expression. I can't possibly be the first person to have noticed this. So why is equality for Arrays defined this way?