20 lines
571 B
Text
20 lines
571 B
Text
/-
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Copyright (c) 2016 Microsoft Corporation. All rights reserved.
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Released under Apache 2.0 license as described in the file LICENSE.
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Authors: Leonardo de Moura, Jeremy Avigad
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The sum type, aka disjoint union.
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-/
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prelude
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import init.logic
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notation A ⊕ B := sum A B
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variables {A B : Type}
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attribute [instance]
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protected definition is_inhabited_left [h : inhabited A] : inhabited (A ⊕ B) :=
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inhabited.mk (sum.inl (default A))
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attribute [instance]
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protected definition is_inhabited_right [h : inhabited B] : inhabited (A ⊕ B) :=
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inhabited.mk (sum.inr (default B))
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