From stdpp Require Import binders strings stringmap. From iris.base_logic Require Import lib.iprop. Require Import lang. Goal ∀ {Σ} (P Q : iProp Σ), ⊢ P -∗ P. move=> Σ P Q. apply: (check_program_spec (Lam "x" (Var "x"))). rewrite /check_program; simpl. done. Qed. Goal ∀ {Σ} (P Q : iProp Σ), ⊢ P -∗ Q -∗ Q ∗ P. move=> Σ P Q. apply: (check_program_spec (Lam "x" (Lam "y" (Pair (Var "y") (Var "x"))))). rewrite /check_program; simpl. done. Qed.