Import int Import real Show 1 + true Variable R : Type Variable T : Type Variable r2t : R -> T Coercion r2t Variable t2r : T -> R Coercion t2r Variable f : T -> R -> T Variable a : T Variable b : R SetOption lean::pp::coercion true SetOption lean::pp::notation false Show f a b Show f b a Variable g : R -> T -> R Infix 10 ++ : f Infix 10 ++ : g Show a ++ b Show b ++ a