[Haskell-beginners] Tree-like Structure with unique elements on each level

[Imants Cekusins]

> data Predicate a = Any | Pred (S.Set a)
data Product a = Pany | Prod (S.Set(Predicate a, S.Set(Product a)))

Does this fit:

data Predicate a = Any | Pred  a
data Product a = Pred' (Predicate a) |  Prod (Product a)

?
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