24 lines
828 B
Text
24 lines
828 B
Text
/-
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Copyright (c) Luke Nelson and Jared Roesch. All rights reserved.
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Released under Apache 2.0 license as described in the file LICENSE.
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Authors: Luke Nelson, Jared Roesch, Sebastian Ullrich, Leonardo de Moura
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-/
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prelude
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import Init.Core
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open Function
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universes u v
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class Functor (f : Type u → Type v) : Type (max (u+1) v) :=
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(map : ∀ {α β : Type u}, (α → β) → f α → f β)
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(mapConst : ∀ {α β : Type u}, α → f β → f α := fun α β => map ∘ const β)
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infixr `<$>` := Functor.map
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@[reducible] def Functor.mapRev {f : Type u → Type v} [Functor f] {α β : Type u} : f α → (α → β) → f β :=
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fun a f => f <$> a
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infixl `<&>` := Functor.mapRev
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def Functor.discard {f : Type u → Type v} {α : Type u} [Functor f] (x : f α) : f PUnit :=
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Functor.mapConst PUnit.unit x
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export Functor (discard)
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