fact: Fixpoint Vfirst_position_aux k n (ys : vector A n) := match ys with | Vnil => None | Vcons y ys' => match P_dec y with | left _ => Some k | _ => Vfirst_position_aux (S k) ys' end end.
imports: Coq(Vector Program Structures.Equalities Morphisms) CoLoR(LogicUtil NatUtil EqUtil ListUtil BoolUtil RelUtil)