(datatype Math
  (Add Math Math)
  (Num i64))
  
(let zero (Num 0))


;; zero here refers to the function/constant zero, not a free variable
(rewrite (Add zero x) x)

(let a (Add (Num 0) (Num 3)))
(let b (Add (Num 7) (Num 9)))
(let c (Num 16))
(union b c)

;; crash if we merge two numbers
(rule (
 (= (Num x) (Num y))
 (!= x y)
)(
 (panic "ahhh")
))
      
      
(run 10)