39 lines
1.1 KiB
Text
39 lines
1.1 KiB
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.control.monad init.data.option.basic
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universes u v
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class HasToBool (α : Type u) :=
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(toBool : α → Bool)
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export HasToBool (toBool)
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instance : HasToBool Bool := ⟨id⟩
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instance {α} : HasToBool (Option α) := ⟨Option.toBool⟩
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@[macroInline] def bool {β : Type u} {α : Type v} [HasToBool β] (f t : α) (b : β) : α :=
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match toBool b with
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| true := t
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| false := f
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@[macroInline] def orM {m : Type u → Type v} {β : Type u} [Monad m] [HasToBool β] (x y : m β) : m β :=
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do b ← x,
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match toBool b with
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| true := pure b
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| false := y
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@[macroInline] def andM {m : Type u → Type v} {β : Type u} [Monad m] [HasToBool β] (x y : m β) : m β :=
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do b ← x,
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match toBool b with
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| true := y
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| false := pure b
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infixl ` <||> `:30 := orM
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infixl ` <&&> `:35 := andM
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@[macroInline] def notM {m : Type → Type v} [Applicative m] (x : m Bool) : m Bool :=
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not <$> x
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