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

data List : U -> U where
  Nil : {a : U} -> List a
  Cons : {a : U} -> a -> List a -> List a

-- Currently if I say _::_ = Cons, it gets curried

infixr 7 _::_
_::_ : {a : U} -> a -> List a -> List a
_::_ x xs = Cons x xs