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

-- TODO this is special cased in some languages, maybe for easier
-- inference? Figure out why.

infixr 0 _$_

_$_ : {a b : U} -> (a -> b) -> a -> b
f $ a = f a