Definition appI : BCI :=
recI (projIs 0)
(compI (succI false) nil [projIs 0])
(compI (succI true)  nil [projIs 0]).
(* Eval vm_compute in inf appI. *)

Lemma appI_correct v1 v2 :
semI appI [v1] [v2] = v1 ++ v2.