case add.h_1 _ _ htl htr rl rr =>
  intros
  contradiction
l r : Exp
lih : typecheck l = Maybe.unknown → ∀ (t : Ty), ¬HasType l t
rih : typecheck r = Maybe.unknown → ∀ (t : Ty), ¬HasType r t
x✝¹ : {{t|HasType l t}}
x✝ : {{t|HasType r t}}
htl : HasType l Ty.nat
htr : HasType r Ty.nat
rl : typecheck l = Maybe.found Ty.nat htl
rr : typecheck r = Maybe.found Ty.nat htr
⊢ Maybe.found Ty.nat (_ : HasType (add l r) Ty.nat) = Maybe.unknown → ∀ (t : Ty), ¬HasType (add l r) t
no goals