lean2/library/standard/option.lean

-- 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

inductive option (A : Type) : Type :=
| none {} : option A
| some    : A → option A

theorem inhabited_option [instance] (A : Type) : inhabited (option A)
:= inhabited_intro none