prop_elementCount :: SetOf e s => s -> Bool
prop_elementCount x =
  let i = size x
  in isFinite i `implies` maybe False (== length (elements x)) (maybeCount i)
prop_elementCount :: SetOf e s => s -> Bool
prop_elementCount x =
  let i = size x
  in isFinite i `implies` maybe False (== length (elements x)) (maybeCount i)
prop_elementCount x =
  let i = size x
  in isFinite i `implies` maybe False (== length (elements x)) (maybeCount i)