import logic data.num open tactic inhabited namespace foo inductive sum (A : Type) (B : Type) : Type := | inl : A → sum A B | inr : B → sum A B theorem inl_inhabited {A : Type} (B : Type) (H : inhabited A) : inhabited (sum A B) := inhabited.destruct H (λ a, inhabited.mk (sum.inl B a)) theorem inr_inhabited (A : Type) {B : Type} (H : inhabited B) : inhabited (sum A B) := inhabited.destruct H (λ b, inhabited.mk (sum.inr A b)) notation `(` h `|` r:(foldl `|` (e r, tactic.or_else r e) h) `)` := r infixl `;`:15 := tactic.and_then definition my_tac := fixpoint (λ t, ( apply @inl_inhabited; t | apply @inr_inhabited; t | apply @num.is_inhabited )) tactic_hint my_tac theorem T : inhabited (sum false num) end foo