{- Convert an `Integer` to an `Optional Natural`, with negative numbers becoming `None Natural`. -} let nonNegative = ./nonNegative sha256:b463373f070df6b1c8c7082051e0810fee38b360bab35256187c8c2b6af5c663 ? ./nonNegative let toNatural : Integer → Optional Natural = λ(n : Integer) → if nonNegative n then Some (Integer/clamp n) else None Natural let example0 = assert : toNatural +7 ≡ Some 7 let example2 = assert : toNatural +0 ≡ Some 0 let example3 = assert : toNatural -3 ≡ None Natural in toNatural