module Prelude

data Nat : U where
  Z : Nat
  S : Nat -> Nat

data Maybe : U -> U where
  Just : {a : U} -> a -> Maybe a
  Nothing : {a : U} -> Maybe a

data Either : U -> U -> U where
  Left : {a b : U} -> a -> Either a b
  Right : {a b : U} -> b -> Either a b