lean2/library/standard/option.lean
Leonardo de Moura 079672f6f9 feat(frontends/lean): add 'class' and 'instances' infrastructure
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-07-04 14:28:09 -07:00

11 lines
361 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
inductive option (A : Type) : Type :=
| none {} : option A
| some : A → option A
theorem inhabited_option [instance] (A : Type) : inhabited (option A)
:= inhabited_intro none