22 lines
493 B
Text
22 lines
493 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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Author: Leonardo de Moura
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-/
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prelude
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import init.logic
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lemma punit_eq (a b : punit) : a = b :=
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punit.rec_on a (punit.rec_on b rfl)
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lemma punit_eq_punit (a : punit) : a = () :=
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punit_eq a ()
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instance : subsingleton punit :=
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subsingleton.intro punit_eq
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instance : inhabited punit :=
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⟨()⟩
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instance : decidable_eq punit :=
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λ a b, is_true (punit_eq a b)
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