/-
Copyright (c) 2016 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Author: Leonardo de Moura
-/
prelude
import init.logic

lemma punit_eq (a b : punit) : a = b :=
punit.rec_on a (punit.rec_on b rfl)

lemma punit_eq_punit (a : punit) : a = () :=
punit_eq a ()

instance : subsingleton punit :=
subsingleton.intro punit_eq

instance : inhabited punit :=
⟨()⟩

instance : decidable_eq punit :=
λ a b, is_true (punit_eq a b)