Function simul_subst_shift

crates/kernel/src/subst.rs:1176–1186

()

    let mut env = InternTable::<Anon>::new();
    let v0 = AE::var(0, ());
    // lift(Var(0), shift=1, cutoff=0) → Var(1)
    let result = lift(&mut env, &v0, 1, 0);
    assert_eq!(result, AE::var(1, ()));
    // lift(Var(0), shift=1, cutoff=1) → Var(0) (below cutoff)
    let result2 = lift(&mut env, &v0, 1, 1);
    assert!(result2.ptr_eq(&v0));
  }

  #[test]
  fn lift_zero_shift() {
    let mut env = InternTable::<Anon>::new();
    let v0 = AE::var(0, ());
    let result = lift(&mut env, &v0, 0, 0);
    assert!(result.ptr_eq(&v0));