-- Copyright (c) 2014 Microsoft Corporation. All rights reserved. -- Released under Apache 2.0 license as described in the file LICENSE. -- Author: Leonardo de Moura import logic.classes.decidable logic.classes.inhabited using decidable namespace unit inductive unit : Type := star : unit notation `⋆`:max := star theorem unit_eq (a b : unit) : a = b := unit_rec (unit_rec (refl ⋆) b) a theorem unit_inhabited [instance] : inhabited unit := inhabited_mk ⋆ theorem decidable_eq [instance] (a b : unit) : decidable (a = b) := inl (unit_eq a b) end unit