lean2/library/standard/logic/classes/inhabited.lean

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-- Copyright (c) 2014 Microsoft Corporation. All rights reserved.
-- Released under Apache 2.0 license as described in the file LICENSE.
-- Authors: Leonardo de Moura, Jeremy Avigad
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import logic.connectives.basic

inductive inhabited (A : Type) : Prop :=
| inhabited_intro : A → inhabited A

theorem inhabited_elim {A : Type} {B : Prop} (H1 : inhabited A) (H2 : A → B) : B :=
inhabited_rec H2 H1

theorem inhabited_Prop [instance] : inhabited Prop :=
inhabited_intro true

theorem inhabited_fun [instance] (A : Type) {B : Type} (H : inhabited B) : inhabited (A → B) :=
inhabited_elim H (take b, inhabited_intro (λa, b))