Section hoas.
Definition mu' := Eval cbn -[enc] in rho (λ mu P n, (P n) (!!K n) (λ Sn, mu P Sn) (!!(ext S) n)).
End hoas.
unfold mu'; Lproc.
Qed.
Hint Resolve mu'_proc : LProc.

Lemma mu'_n_true (n:nat): P (ext n)  == ext true -> mu' P (ext n) == ext n.