{-
Returns `True` if the supplied function returns `True` for a present element and
`False` otherwise
-}
let any
    : ∀(a : Type) → (a → Bool) → Optional a → Bool
    =   λ(a : Type)
      → λ(f : a → Bool)
      → λ(xs : Optional a)
      → merge { Some = f, None = False } xs

let example0 = assert : any Natural Natural/even (Some 2) ≡ True

let example1 = assert : any Natural Natural/even (None Natural) ≡ False

in  any