Is there a way to get this to work?

data A = Aconstructor Int
data B = Bconstructor Int
data AorB = A | B

f :: Int -> AorB
f x
| even x = Aconstructor x
| otherwise = Bconstructor x

I get this diagnostic.

Couldn't match expected type `AorB' against inferred type `A'

Since AorB is A or B, why is this not permitted?

If instead I write

data AorB = Aconstructor Int | Bconstructor Int

everything works out ok. But what if I want separate types for A and B?

Thanks,

-- Russ