import standard using tactic inductive sum (A 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_elim H (λ a, inhabited_intro (inl B a)) theorem inr_inhabited (A : Type) {B : Type} (H : inhabited B) : inhabited (sum A B) := inhabited_elim H (λ b, inhabited_intro (inr A b)) definition my_tac := fixpoint (λ t, [ apply @inl_inhabited; t | apply @inr_inhabited; t | apply @num.inhabited_num ]) tactic_hint [inhabited] my_tac theorem T : inhabited (sum false num.num)