23 lines
652 B
Text
23 lines
652 B
Text
-- 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
|
|
open decidable
|
|
|
|
inductive unit : Type :=
|
|
star : unit
|
|
namespace unit
|
|
notation `⋆`:max := star
|
|
|
|
theorem equal [protected] (a b : unit) : a = b :=
|
|
rec (rec rfl b) a
|
|
|
|
theorem eq_star (a : unit) : a = star :=
|
|
equal a star
|
|
|
|
theorem is_inhabited [protected] [instance] : inhabited unit :=
|
|
inhabited.mk ⋆
|
|
|
|
theorem has_decidable_eq [protected] [instance] (a b : unit) : decidable (a = b) :=
|
|
inl (equal a b)
|
|
end unit
|