------------------------------------------------------------------------------------------------------ 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.inhabited inductive option (A : Type) : Type := | none {} : option A | some : A → option A theorem inhabited_option [instance] (A : Type) : inhabited (option A) := inhabited_intro none