(* ------------------------------------------------------------------------- *)
(* General tactics *)

Ltac genclear H := generalize H; clear H.Ltac clearall :=
   repeat
        match goal with [H : _ |- _ ] => clear H end
     || match goal with [H : _ |- _ ] => genclear H end.CoInductive infseq : Type := Cons : T -> infseq -> infseq.CoInductive infseq : Type := Cons : T -> infseq -> infseq.Definition hd (s:infseq) : T := match s with Cons x _ => x end.Definition tl (s:infseq) : infseq := match s with Cons _ s => s end.

Lemma recons : forall s, Cons (hd s) (tl s) = s.